Abstract: Aiming at the steering vector mismatch caused by the angle error of the desired signal and the rapid change of the interference, a novel null broadening robust adaptive beamforming algorithm was proposed in this paper. Firstly, a covariance matrix was reconstructed for the received signal, and then the flattened main lobe beam was constrained according to the approximate desired signal angle. Finally, an iterative algorithm was proposed to solve the non-convex optimization problem after the above processing steps. The simulation results show that the proposed algorithm has better robustness than the traditional algorithm to the mismatch of signal angle and the rapid change of interference. Being applicable to arbitrary arrays, the algorithm possesses great practical significance in engineering.