The invention relates to a GSM (Global System for Mobile Communications) base station, a communication system and a data transmission method. The GSM base station comprises a wired interface, an antenna and a mobile phone chip module, wherein the mobile phone chip module is connected with the wired interface and the antenna, and comprises at least two mobile phone chips; each mobile phone chip is used for receiving uplink data from the antenna, adding the unique identification number of the mobile phone chip into the uplink data, transmitting the uplink data to the wired interface, and transmitting downlink data from the wired interface through the antenna after the downlink data is received; and the wired interface is used for acquiring the unique identification number carried by the downlink data after the download data is received, and transmitting the downlink data to a mobile phone chip corresponding to the unique identification number. A conventional base station chip is replaced by combination of at least two mobile phone chips, so that the hardware cost of a base station can be lowered greatly.