Abstract: Because the traditional adaptive beamformer suffers from the output performance degradation and even interference suppression failure when the position of the coherent interference moves, an adaptive beam-forming of coherent signals with null widening is proposed. Firstly, this algorithm forms a Toeplitz matrix based on covariance matrix of received data. Then the interference-plus-noise covariance matrix is reconstructed and optimized. At last, null widening technique and diagonal loading technique are used in the covariance matrix. The simulation results show that the algorithm can not only broaden beam null width adaptively when desired signal and interference are coherent, but also control the width and depth of the null, Compared with Mailloux algorithm, the proposed method can obtain lower sidelobe level and higher output SINR in the case of high input SNR.