Provided is a full-time duplex system. The system includes: a receiving antenna (107), a transmitting antenna (108), a transmitting channel (109), an LNA (106), a mode determination unit (101), a power detection amplitude phase adjustment unit (102), an RSSI detection amplitude phase adjustment unit (103) and an amplitude phase unit (104); the power detection amplitude phase adjustment unit (102) is electrically connected between the receiving antenna (107) and the low noise amplifier (106) and also between the transmitting antenna (108) and the transmitting channel (109); the mode determination unit (101) notifies, according to a power range which a signal transmitting power of the full-time duplex system belongs to, one of the power detection amplitude phase adjustment unit (102) or the RSSI detection amplitude phase adjustment unit (103) of controlling the amplitude phase unit (104) to adjust an amplitude and a phase of a transmitting cancellation signal.