The main card of China Merchants Credit Card refers to the bank card that plays a leading role by using multiple bank cards under the same account of China Merchants Bank, and the cardholder of the main card needs to bear all the debts under the sub-card. Corresponding to the main card is the secondary card, which shares a credit line with the main card. Usually, the main card is held by the applicant of the main card, whose identity is generally parents, and the holder of the auxiliary card is generally children.