The present invention relates to the field of network communications, and discloses a duplex mode adaptive method, including: querying the modulation mode configuration table, to obtain a maximum modulation mode of the current duplex mode and a maximum modulation mode of the non-current duplex mode; calculating maximum spectral efficiency of the current duplex mode according to the maximum modulation mode of the current duplex mode; calculating maximum spectral efficiency of the non-current duplex mode according to the maximum modulation mode of the non-current duplex mode; comparing the maximum spectral efficiency of the current duplex mode with the maximum spectral efficiency of the non-current duplex mode, and selecting a duplex mode whose spectral efficiency is greater as a next-step duplex mode; and switching a duplex mode of the wireless communications apparatus to the next-step duplex mode.