A method and an apparatus for adjusting a transmit power in GSM. The method includes: determining that a communications terminal concurrently executes services respectively on a first SIM card and a second SIM card that are supported by the communications terminal, where the service executed on the first SIM card is a first service, and the service executed on the second SIM card is a second service, a modem corresponding to the first SIM card is a first modem, and a modem corresponding to the second SIM card is a second modem; and further, adjusting steady-state transmit powers of modems according to a service type of the first service and a service type of the second service.