diff --git a/ccdi-project/src/main/resources/mapper/ccdi/project/CcdiBankStatementMapper.xml b/ccdi-project/src/main/resources/mapper/ccdi/project/CcdiBankStatementMapper.xml
index 1720917d..f1d8ff69 100644
--- a/ccdi-project/src/main/resources/mapper/ccdi/project/CcdiBankStatementMapper.xml
+++ b/ccdi-project/src/main/resources/mapper/ccdi/project/CcdiBankStatementMapper.xml
@@ -403,7 +403,7 @@ PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
             )
         </foreach>
         on duplicate key update
-            bank_statement_id = bank_statement_id
+            batch_id = batch_id
     </insert>
 
     <delete id="deleteByProjectIdAndBatchId">
diff --git a/ccdi-project/src/test/java/com/ruoyi/ccdi/project/mapper/CcdiBankStatementMapperXmlTest.java b/ccdi-project/src/test/java/com/ruoyi/ccdi/project/mapper/CcdiBankStatementMapperXmlTest.java
index d1dd33ae..49539bf1 100644
--- a/ccdi-project/src/test/java/com/ruoyi/ccdi/project/mapper/CcdiBankStatementMapperXmlTest.java
+++ b/ccdi-project/src/test/java/com/ruoyi/ccdi/project/mapper/CcdiBankStatementMapperXmlTest.java
@@ -132,6 +132,17 @@ class CcdiBankStatementMapperXmlTest {
         }
     }
 
+    @Test
+    void insertBatch_shouldAvoidUpdatingAutoIncrementPrimaryKeyInDuplicateBranch() throws Exception {
+        try (InputStream inputStream = getClass().getClassLoader().getResourceAsStream(RESOURCE)) {
+            String xml = new String(inputStream.readAllBytes(), StandardCharsets.UTF_8);
+
+            assertTrue(xml.contains("on duplicate key update"), xml);
+            assertTrue(xml.contains("batch_id = batch_id"), xml);
+            assertFalse(xml.contains("bank_statement_id = bank_statement_id"), xml);
+        }
+    }
+
     private MappedStatement loadMappedStatement(String statementId) throws Exception {
         Configuration configuration = new Configuration();
         configuration.setEnvironment(new Environment("test", new JdbcTransactionFactory(), new NoOpDataSource()));
diff --git a/docs/reports/implementation/2026-03-20-bank-statement-mysql1869-fix.md b/docs/reports/implementation/2026-03-20-bank-statement-mysql1869-fix.md
new file mode 100644
index 00000000..2fcb2e02
--- /dev/null
+++ b/docs/reports/implementation/2026-03-20-bank-statement-mysql1869-fix.md
@@ -0,0 +1,54 @@
+# 银行流水批量入库 MySQL 1869 修复记录
+
+## 背景
+
+文件上传解析完成后，`CcdiFileUploadServiceImpl.fetchAndSaveBankStatements` 调用
+`CcdiBankStatementMapper.insertBatch` 批量写入 `ccdi_bank_statement`。
+线上报错如下：
+
+- MySQL 错误码：`1869`
+- 异常信息：`Auto-increment value in UPDATE conflicts with internally generated values`
+
+## 根因
+
+`ccdi-project/src/main/resources/mapper/ccdi/project/CcdiBankStatementMapper.xml`
+中的批量插入 SQL 使用了 no-op upsert：
+
+```sql
+ON DUPLICATE KEY UPDATE
+  bank_statement_id = bank_statement_id
+```
+
+`bank_statement_id` 是自增主键。当前 MySQL 版本在 `INSERT ... ON DUPLICATE KEY UPDATE`
+场景下，若 duplicate 分支显式更新自增列，即使是自赋值，也会触发 `1869`。
+
+## 本次修改
+
+1. 将 `insertBatch` 的 duplicate 分支从自增主键自赋值改为普通字段自赋值：
+
+```sql
+ON DUPLICATE KEY UPDATE
+  batch_id = batch_id
+```
+
+2. 新增 Mapper XML 回归测试，约束批量去重 SQL 不得再更新自增主键。
+
+## 影响说明
+
+- 新流水：仍正常插入。
+- 重复流水：仍按唯一键命中后跳过，不改写已有业务数据。
+- 非重复键的其他 SQL 错误：仍然继续抛出，不会被静默吞掉。
+
+## 验证
+
+执行命令：
+
+```bash
+mvn test -pl ccdi-project -Dtest=CcdiBankStatementMapperXmlTest,CcdiFileUploadServiceImplTest
+```
+
+重点关注：
+
+- `insertBatch_shouldAvoidUpdatingAutoIncrementPrimaryKeyInDuplicateBranch`
+- `processFileAsync_shouldMarkParsedFailedWhenInsertBatchThrowsUnexpectedSqlError`
+