Embodiments of the present invention provide a method for reducing a self-interference signal in a communications system, and an apparatus. The method includes: sending a sounding signal and a first communication signal; receiving an input signal; separating a near-field reflection signal corresponding to the sounding signal from an echo signal of the input signal; determining, based on the near-field reflection signal, a near-field reflection channel parameter; determining, based on the near-field reflection channel parameter, a reconstructed near-field reflected self-interference signal; and subtracting the reconstructed near-field reflected self-interference signal from a received second communication signal. The present invention can effectively recognize and reconstruct a near-field reflection signal, thereby reducing a near-field reflected self-interference signal in self-interference.