diff --git a/blade-service-api/blade-system-api/src/main/java/org/springblade/system/pojo/entity/Dept.java b/blade-service-api/blade-system-api/src/main/java/org/springblade/system/pojo/entity/Dept.java
index 15a3e94a..e5958c76 100644
--- a/blade-service-api/blade-system-api/src/main/java/org/springblade/system/pojo/entity/Dept.java
+++ b/blade-service-api/blade-system-api/src/main/java/org/springblade/system/pojo/entity/Dept.java
@@ -150,6 +150,13 @@ public class Dept extends TenantEntity {
 	@Schema(description = "合同编码前缀")
 	private String contractCodePrefix;
 
+	/**
+	 * 合同初始流水号（该部门当年首个合同时从此号起编，范围1-999）
+	 */
+	@Schema(description = "合同初始流水号")
+	@TableField(updateStrategy = FieldStrategy.ALWAYS)
+	private Integer contractInitialSerial;
+
 	/**
 	 * 组织简称
 	 */
diff --git a/blade-service/blade-system/src/main/java/org/springblade/system/mapper/DeptMapper.xml b/blade-service/blade-system/src/main/java/org/springblade/system/mapper/DeptMapper.xml
index f45626dd..bfbaf61f 100644
--- a/blade-service/blade-system/src/main/java/org/springblade/system/mapper/DeptMapper.xml
+++ b/blade-service/blade-system/src/main/java/org/springblade/system/mapper/DeptMapper.xml
@@ -14,6 +14,7 @@
         <result column="dept_code" property="deptCode"/>
         <result column="kingdee_dept_code" property="kingdeeDeptCode"/>
         <result column="contract_code_prefix" property="contractCodePrefix"/>
+        <result column="contract_initial_serial" property="contractInitialSerial"/>
         <result column="short_name" property="shortName"/>
         <result column="pinyin_mnemonic" property="pinyinMnemonic"/>
         <result column="mnemonic_code" property="mnemonicCode"/>
@@ -36,6 +37,7 @@
         <result column="dept_code" property="deptCode"/>
         <result column="kingdee_dept_code" property="kingdeeDeptCode"/>
         <result column="contract_code_prefix" property="contractCodePrefix"/>
+        <result column="contract_initial_serial" property="contractInitialSerial"/>
         <result column="short_name" property="shortName"/>
         <result column="pinyin_mnemonic" property="pinyinMnemonic"/>
         <result column="mnemonic_code" property="mnemonicCode"/>
diff --git a/blade-service/blade-system/src/main/java/org/springblade/system/service/impl/DeptServiceImpl.java b/blade-service/blade-system/src/main/java/org/springblade/system/service/impl/DeptServiceImpl.java
index 3dda7348..dd24564f 100644
--- a/blade-service/blade-system/src/main/java/org/springblade/system/service/impl/DeptServiceImpl.java
+++ b/blade-service/blade-system/src/main/java/org/springblade/system/service/impl/DeptServiceImpl.java
@@ -687,6 +687,7 @@ public class DeptServiceImpl extends ServiceImpl<DeptMapper, Dept> implements ID
 		}
 		validateDeptCategory(dept);
 		validateDeptCode(dept, parent);
+		validateContractInitialSerial(dept);
 		return saveOrUpdate(dept);
 	}
 
@@ -874,6 +875,16 @@ public class DeptServiceImpl extends ServiceImpl<DeptMapper, Dept> implements ID
 		}
 	}
 
+	private void validateContractInitialSerial(Dept dept) {
+		Integer serial = dept.getContractInitialSerial();
+		if (serial == null) {
+			return;
+		}
+		if (serial < 1 || serial > 999) {
+			throw new ServiceException("合同初始流水号范围为1到999");
+		}
+	}
+
 	private void validateDeptCode(Dept dept, Dept parent) {
 		String deptCode = dept.getDeptCode();
 		// 组织编码非必填，为空时存 null，避免唯一索引冲突
diff --git a/blade-service/blade-transport/src/main/java/org/springblade/transport/service/impl/ContractManageServiceImpl.java b/blade-service/blade-transport/src/main/java/org/springblade/transport/service/impl/ContractManageServiceImpl.java
index 1ec56fd9..9d36d811 100644
--- a/blade-service/blade-transport/src/main/java/org/springblade/transport/service/impl/ContractManageServiceImpl.java
+++ b/blade-service/blade-transport/src/main/java/org/springblade/transport/service/impl/ContractManageServiceImpl.java
@@ -298,6 +298,7 @@ public class ContractManageServiceImpl extends BaseServiceImpl<ContractManageMap
 		validateBillingPlans(request.getBillingPlanJson());
 		validatePaymentRatios(request.getPaymentRatioJson());
 		Map<String, Object> beforeData = buildContractChangeSnapshot(source);
+		applyContractNo(source, request.getContractNo(), false);
 		source.setContractName(request.getContractName()); source.setPartyB(request.getPartyB());
 		source.setStartDate(request.getStartDate()); source.setEndDate(request.getEndDate()); source.setContractFormat(request.getContractFormat());
 		source.setSettlementMode(request.getSettlementMode()); source.setLegalSealFlag(request.getLegalSealFlag()); source.setCopyCount(request.getCopyCount());
@@ -507,8 +508,7 @@ public class ContractManageServiceImpl extends BaseServiceImpl<ContractManageMap
 				contractManage.setOrganizationId(TransportBusinessSupport.currentDeptId("合同管理"));
 				contractManage.setOrganizationName(TransportBusinessSupport.currentDept("合同管理").getDeptName());
 			}
-			// 新增始终按部门规则生成合同编号，避免前端预览号并发冲突
-			contractManage.setContractNo(nextContractNo(contractManage.getOrganizationId()));
+			applyContractNo(contractManage, contractManage.getContractNo(), true);
 			if (Func.isEmpty(contractManage.getHandlerUserId())) {
 				contractManage.setHandlerUserId(AuthUtil.getUserId());
 				contractManage.setHandlerUserName(AuthUtil.getUserName());
@@ -516,7 +516,7 @@ public class ContractManageServiceImpl extends BaseServiceImpl<ContractManageMap
 			contractManage.setArchiveStatus(ARCHIVE_STATUS_PENDING);
 		} else {
 			ContractManage oldRecord = loadExists(contractManage.getId());
-			contractManage.setContractNo(oldRecord.getContractNo());
+			applyContractNo(contractManage, contractManage.getContractNo(), false);
 			if (Func.isEmpty(contractManage.getOrganizationId())) {
 				contractManage.setOrganizationId(oldRecord.getOrganizationId());
 				contractManage.setOrganizationName(oldRecord.getOrganizationName());
@@ -535,6 +535,28 @@ public class ContractManageServiceImpl extends BaseServiceImpl<ContractManageMap
 		}
 	}
 
+	/**
+	 * 保存合同编号。新增未填写时按部门规则生成，已填写或编辑时保留手工编号并校验唯一。
+	 */
+	private void applyContractNo(ContractManage contractManage, String contractNo, boolean generateWhenEmpty) {
+		String normalizedContractNo = TransportBusinessSupport.trimToNull(contractNo);
+		if (Func.isEmpty(normalizedContractNo)) {
+			if (!generateWhenEmpty) {
+				throw new ServiceException("请输入合同编号");
+			}
+			normalizedContractNo = nextContractNo(contractManage.getOrganizationId());
+		}
+		TransportBusinessSupport.validateLength(normalizedContractNo, 100, "合同编号不能超过100字");
+		Long duplicatedCount = count(Wrappers.<ContractManage>lambdaQuery()
+			.eq(ContractManage::getIsDeleted, 0)
+			.eq(ContractManage::getContractNo, normalizedContractNo)
+			.ne(Func.isNotEmpty(contractManage.getId()), ContractManage::getId, contractManage.getId()));
+		if (duplicatedCount != null && duplicatedCount > 0) {
+			throw new ServiceException("合同编号已存在");
+		}
+		contractManage.setContractNo(normalizedContractNo);
+	}
+
 	@Override
 	public synchronized String nextContractNo(Long organizationId) {
 		if (Func.isEmpty(organizationId)) {
@@ -558,7 +580,8 @@ public class ContractManageServiceImpl extends BaseServiceImpl<ContractManageMap
 			.orderByDesc(ContractManage::getContractNo)
 			.last("LIMIT 50"));
 		Pattern pattern = Pattern.compile("^" + Pattern.quote(prefix) + "（" + year + "）(\\d{3})号$");
-		int next = 1;
+		// 当年尚无匹配编号时，从组织配置的初始流水号起编；否则在已有最大流水号上加1
+		int next = resolveContractInitialSerial(dept);
 		for (ContractManage item : latestList) {
 			String contractNo = TransportBusinessSupport.trimToNull(item.getContractNo());
 			if (Func.isEmpty(contractNo)) {
@@ -577,6 +600,17 @@ public class ContractManageServiceImpl extends BaseServiceImpl<ContractManageMap
 		return head + String.format("%03d", next) + "号";
 	}
 
+	private int resolveContractInitialSerial(Dept dept) {
+		Integer serial = dept.getContractInitialSerial();
+		if (serial == null || serial < 1) {
+			return 1;
+		}
+		if (serial > 999) {
+			throw new ServiceException("组织机构中配置的合同初始流水号不能超过999");
+		}
+		return serial;
+	}
+
 	private void refreshArchiveStatusOnApprove(ContractManage contractManage) {
 		if (hasSealArchiveFile(contractManage.getContractFileJson())) {
 			contractManage.setArchiveStatus(ARCHIVE_STATUS_ARCHIVED);
@@ -1015,6 +1049,7 @@ public class ContractManageServiceImpl extends BaseServiceImpl<ContractManageMap
 
 	private Map<String, Object> buildContractChangeSnapshot(ContractManage contractManage) {
 		Map<String, Object> data = new LinkedHashMap<>();
+		data.put("contractNo", contractManage.getContractNo());
 		data.put("contractName", contractManage.getContractName());
 		data.put("partyB", contractManage.getPartyB());
 		data.put("startDate", contractManage.getStartDate());
diff --git a/doc/sql/bladex/bladex.mysql.all.create.sql b/doc/sql/bladex/bladex.mysql.all.create.sql
index 7a6e69cc..fed3b1b5 100644
--- a/doc/sql/bladex/bladex.mysql.all.create.sql
+++ b/doc/sql/bladex/bladex.mysql.all.create.sql
@@ -305,6 +305,7 @@ CREATE TABLE `blade_dept`  (
   `dept_code` varchar(30) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '组织编码',
   `kingdee_dept_code` varchar(64) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '金蝶部门代码',
   `contract_code_prefix` varchar(64) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '合同编码前缀',
+  `contract_initial_serial` int NULL DEFAULT NULL COMMENT '合同初始流水号',
   `short_name` varchar(45) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '组织简称',
   `pinyin_mnemonic` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '拼音助记码',
   `mnemonic_code` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '助记码',
diff --git a/doc/sql/transport/blade_dept_contract_initial_serial_20261020.sql b/doc/sql/transport/blade_dept_contract_initial_serial_20261020.sql
new file mode 100644
index 00000000..7b4ac000
--- /dev/null
+++ b/doc/sql/transport/blade_dept_contract_initial_serial_20261020.sql
@@ -0,0 +1,3 @@
+-- 组织机构新增合同初始流水号：该部门当年首个合同从此流水号起编，后续递增
+ALTER TABLE `blade_dept`
+  ADD COLUMN `contract_initial_serial` int(11) DEFAULT NULL COMMENT '合同初始流水号' AFTER `contract_code_prefix`;