The invention relates to radio modem and TD-LTE systems in the field of wireless communication, and specifically relates to a radio modem and power TD-LTE private network common antenna system and an implementation method thereof. The system comprises a radio modem base station and a power TD-LTE private network base station. A common combiner is arranged at the output ports of the radio modem base station and the power TD-LTE private network base station. The output of the common combiner is connected with an antenna for realizing a transceiver common antenna of the radio modem base station and the power TD-LTE private network base station. The invention also provides the implementation method of the radio modem and power TD-LTE private network common antenna system. According to the invention, by adding the combiner, radio frequency signals of the radio modem and the power TD-LTE are transmitted through a set of antennas. According to the invention, the existing base station site of the radio modem and an antenna feed system are utilized, the power TD-LTE and radio modem common site common antenna construction can be realized, and the network construction cost can be effectively reduced.