A method for a GSM/CDMA dual-mode mobile phone to control two GSM subscriber identification modules is provided. Without changing hardware of the GSM/CDMA dual-mode mobile phone, the method uses a GSM control module to operate a first GSM subscriber identification module, and a CDMA UART driver module and a SIM/UIM driver module connected with each other are built in a CDMA control module. The CDMA URAT driver module is communicated with a GSM device driver layer of the GSM control module through a UART standard, such that the GSM control module is able to control a second GSM subscriber identification module connected to the SIM/UIM driver module. Thus, the GSM/CDMA dual-mode mobile phone is able to control two GSM subscriber identification modules so as to satisfy needs and demands for businessmen and lovers in personal style.