Abstract: The direction-Of-Arrival(DOA) estimation algorithm named Sdp-CBF combining conventional beamforming and semidefinite programming is proposed in this paper,which can be used for the azimuth super-resolution estimation of underwater targets.The Sdp-CBF algorithm obtains multi-target azimuth spectrum data based on conventional beamforming,and uses the array response matrix and semi-definite programming techniques to accurately estimate the target number and direction of arrival.By calculating the conventional beampattern matrix and azimuth spectrum of a given array,Sdp-CBF azimuth spectrum is obtained by quadratic programming.The algorithm does not require subspace decomposition and can be applied to any noise signal model.Sdp-CBF algorithm is suitable for arbitrary noise model,and super-resolution bearing estimation is obtained based on array characteristics and signal energy information.The simulation results show that Sdp-CBF algorithm also has strong noise suppression ability and can effectively reduce the background level of azimuth spectrum,the azimuth resolution performance in low SNR environment is better than that of the classical high-resolution algorithms such as MUSIC.The results of the anechoic pool test data and lake test data show that the algorithm has a strong resolution for weak signals in complex environments.