The application method of CCB credit card supplementary card is: 1. Handling at CCB outlets: If it is necessary to handle supplementary credit card, applicants for the main card and supplementary card should bring their valid identity documents to CCB outlets and obey the instructions of the staff at the outlets; 2. Online processing: log in to the credit card website of CCB and click "Online Credit Card Application" on the page to apply for a credit card sub-card. However, it should be noted that some credit card types do not support online processing of credit card sub-cards, so in this case, you need to bring valid certificates to the bank outlets for processing.