The method of mutual coupling correction of array output signal is studied in the paper. According to array signal processing's feature, array error model is analyzed and array mutual coupling is studied. The method that smart antennas' channel calibration by BP network in wireless communication is proposed, which improves the accuracy of algorithms, such as the DOA estimation algorithm, Beam Forming algorithm etc.8-unit uniform linear array and 8-unit uniform circular array are simulated by computer, and the results are compared with spatial spectrum lines of before-after correction. The proposed method is effective, for computer simulation experimental results are in line with the theoretical ones.