A dual mode mobile terminal system includes an antenna, a diplexer, a first communication module, a first power amplifier, and a second communication module. The diplexer receives and transmits a first wireless signal, and isolates the receiving path and the transmitting path of the first wireless signal. The second communication module receives a second wireless signal from the switch. The first power amplifier amplifies the second wireless signal. The antenna is selectably connected to the diplexer or the first power amplifier through the switch. The antenna, the switch, the diplexer, and the first communication module form a first signal transmission path to transmit and receive the first wireless signal; the antenna, the switch, the first power amplifier, and the second communication module form a second signal transmission path to transmit and receive the second wireless signal.