In digital array radar (DAR), channel mismatch has a serious impact on many indicators such as low sidelobe beamforming, signal to interference ratio of output signal and anti-interference. To correct the error, the channel equalization technique is gradually applied to the array error correction and has been rapidly developed. The current channel equalization techniques are divided into time domain least square fitting method, frequency domain least square fitting method and Fourier transform method according to the equalizer weight coefficient solving method. The main principles and difficulties of each method are analyzed emphatically, and the advantages and disadvantages of various methods are compared. The difficulties of the digital array radar channel equalization technique in future development are summarized.