Due to the unequal characteristic of equivalent positive and negative sequence impedance of the DC side system during the fault period, the traditional current mutation phase selector applied to the receiver AC line has some adaptability problems. In this paper, the problem of wrong phase selection of traditional current mutation phase selection element in AC/DC hybrid system is deeply analyzed, and an improved current mutation phase selector is proposed. The traditional phase current mutation is improved by current compensation method, and the phase selection coefficient is constructed by the improved phase current mutation, and the fault phase selection is carried out according to the amplitude relation of the phase selection coefficient, so as to compensate the effect of the unequal equivalent positive and negative sequence impedance on the DC side in principle. Simulation results show that the improved phase selector could quickly and accurately select the fault phase during the failure of the receiver AC line, and the phase selector would have good resistance to transition resistance.