diff --git a/src/main/java/com/ai/da/service/impl/AccountServiceImpl.java b/src/main/java/com/ai/da/service/impl/AccountServiceImpl.java
index 1836d0d1..f2e17bcf 100644
--- a/src/main/java/com/ai/da/service/impl/AccountServiceImpl.java
+++ b/src/main/java/com/ai/da/service/impl/AccountServiceImpl.java
@@ -2442,7 +2442,7 @@ public class AccountServiceImpl extends ServiceImpl<AccountMapper, Account> impl
                     throw new BusinessException("Insufficient credits (Balance: " + remainingCredits + ").", ResultEnum.PROMPT.getCode());
                 }
                 subAccount.setCreditsUsageLimit(addSubAccountDTO.getCreditsUsageLimit());
-                subAccount.setCreditsUsage(addSubAccountDTO.getCreditsUsage());
+                subAccount.setCreditsUsage(Objects.isNull(addSubAccountDTO.getCreditsUsage()) ? BigDecimal.ZERO : addSubAccountDTO.getCreditsUsage());
                 if (Objects.nonNull(subAccount.getCredits())) {
                     subAccount.setCredits(subAccount.getCreditsUsageLimit().add(subAccount.getCredits()));
                 }else {
@@ -2667,7 +2667,7 @@ public class AccountServiceImpl extends ServiceImpl<AccountMapper, Account> impl
         for (Long id : addSubAccountDTO.getDeleteIdList()) {
             Account account = baseMapper.selectById(id);
             if (Objects.nonNull(account.getParentId()) && account.getParentId().equals(adminAccId)) {
-                BigDecimal unusedCredits = account.getCreditsUsageLimit().subtract(account.getCreditsUsage());
+                BigDecimal unusedCredits = account.getCreditsUsageLimit().subtract(Objects.isNull(account.getCreditsUsage()) ? BigDecimal.ZERO : account.getCreditsUsage());
                 BigDecimal finalCredits = calculateFinalCredits(account, unusedCredits);
 
                 int userRole = determineUserRole(account.getId());