China Merchants Bank is my salary card, but why does its query always show that the balance is insufficient?

Your question is not clear. Have you checked the account balance? Maybe your salary has not been credited. If there is 100 yuan in the card, you need to withdraw 1000 yuan to show that the balance is insufficient. Another possibility is that your account balance is negative after deducting the annual fee. Suppose you deposit 1000 yuan, but the actual account does not have 1000 yuan.