The invention relates to a multi-data-module shared radio frequency antenna communication system which comprises an external antenna, an external power divider, a switch and N groups of power divider units. A main antenna is connected to an input end of the external power divider; an external antenna of an auxiliary antenna, which is connected to the external power divider, is connected to the switch; an nth path of power division output end of the external power divider is connected to an input end of one antenna signal power divider in an nth group of power divider unit, and the external power divider is connected with N-1 groups of power divider units at most; and an nth output end of the switch is connected to a combining input end of the other antenna power divider in the nth group of power divider unit. A multi-data-module shared radio frequency antenna communication method comprises the steps of: according to a number m of accessed wireless communication units, regulating a number of antenna power dividers connected to the output ends of the external power divider; and controlling a turn-on path of the switch and the communication units. The system uses one auxiliary external antenna, supports expansion of the communication units and a communication module, and can achieve an effect that multiple data modules share one auxiliary external antenna to carry out communication.