A communication system for sharing of a radio frequency antenna by multiple data modules. The communication system comprises external antennas, i.e. primary and secondary antennas, an external power divider, a switching switch, and N groups of power divider units. The power divider units comprise two antenna signal power dividers, and each group of power divider units corresponds to a group of communication units. The communication units comprise multiple communication modules, and each of the communication modules comprise a SIM card. The primary antenna is connected to an input terminal of the external power divider, and the secondary antenna is connected to the switching switch. In a communication method based on the above system, the number of antenna signal power dividers connected to an output terminal of the external power divider is adjusted according to the number of connected wireless communication units, so as to control a connection path between the switching switch and the communication units. The present application uses one external antenna, supports expansion of communication units and communication modules and can realize sharing of one external antenna by multiple data modules for communication.