The invention discloses a testing system for radio frequency consistency of a satellite mobile communication terminal and a testing method of the testing system. The system comprises a logic channel information generator, a frequency correction channel modulation module, another service and control channel modulation module, a channel multiplexing module, a radio frequency up-conversion module, a satellite-to-ground channel simulator, a duplexer, an attenuator, a radio frequency down-conversion module, a channel demultiplexing module, a terminal random access channel demodulation module, a terminal service data channel information acquisition module and a radio frequency consistency testing module. The testing system constructs a satellite-to-ground channel environment by matching the satellite-to-ground channel simulator with the radio frequency up-conversion module, the radio frequency down-conversion module and the attenuator, and simulates a ground station to test the satellite mobile communication terminal. The testing system tests the radio frequency consistency of the satellite mobile communication terminal, is simple in structure and easy to realize, and can lower the testing cost, thereby promoting industrial development of satellite mobile communication.