First, enter the mobile phone system, find the Changchun citizen card APP, and click the Changchun citizen card APP to enter. Enter the Changchun citizen card APP, select the corresponding login method and log in the account. If you don't have an account, you need to register an account to log in. After successfully logging in to Changchun Citizen Card APP, find the mine, click Security, click Real Name Authentication, and account real name authentication to handle related business. When finished, click My, find the settings above, and click Enter. Enter the settings, find the registered mobile phone number modification, and click the registered mobile phone number modification to enter. Pop-up window, enter the payment password, and click OK in the lower right corner to enter. Enter the registered mobile phone number to be modified, enter a new mobile phone number, and click Modify below to modify the mobile phone number.