This means that you may have overpaid the previous bill, resulting in overpayment, and there is no consumption in this period, so the bill shows a negative number (if you still owe money, it shows a positive number).

The Credit Card Customer Service Center of China Merchants Bank was awarded as the "Best Call Center of the Year in China" at the China Conference on Call Center Operation and Customer Relationship Management in 2004, and it is the only award-winning unit in the domestic financial industry. In 2002, China Merchants Bank realized the integration and professional service of credit cards.

References:

Baidu Encyclopedia-China Merchants Bank Credit Card