A method for adaptive duplex mode selection, the method comprising: obtaining a modulation mode configuration table, information about self-interference isolation, and information about a transmitted signal and information about a received signal of a wireless communications apparatus; said method being characterized by: calculating signal quality of a current duplex mode according to the current duplex mode, the information about self-interference isolation, and the information about the transmitted signal and the information about the received signal; and predicting signal quality of a non-current duplex mode according to the non-current duplex mode, the information about self-interference isolation, and the information about the transmitted signal and the information about the received signal; querying the modulation mode configuration table according to the signal quality of the current duplex mode and the signal quality of the non-current duplex mode, 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, and 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. obtaining a modulation mode configuration table, information about self-interference isolation, and information about a transmitted signal and information about a received signal of a wireless communications apparatus; said method being characterized by: calculating signal quality of a current duplex mode according to the current duplex mode, the information about self-interference isolation, and the information about the transmitted signal and the information about the received signal; and predicting signal quality of a non-current duplex mode according to the non-current duplex mode, the information about self-interference isolation, and the information about the transmitted signal and the information about the received signal; querying the modulation mode configuration table according to the signal quality of the current duplex mode and the signal quality of the non-current duplex mode, 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, and 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. calculating signal quality of a current duplex mode according to the current duplex mode, the information about self-interference isolation, and the information about the transmitted signal and the information about the received signal; and predicting signal quality of a non-current duplex mode according to the non-current duplex mode, the information about self-interference isolation, and the information about the transmitted signal and the information about the received signal; querying the modulation mode configuration table according to the signal quality of the current duplex mode and the signal quality of the non-current duplex mode, 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, and 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.