Abstract: In order to improve the performance of adaptive beamformer in the presence of steering vector mismatch, a robust adaptive beamforming method is proposed. In our method, the Minimum Variance Distortionless Response (MVDR) beamformer is designed on the basis of signal steering vector estimation, which is obtained adaptively from array data covariance matrix with beam space power constraint by the use of iterative second-order cone program. It is shown that steering vector of signal can be accurately estimated even when severe mismatch exists, which ensures that signal component will pass through without distortion. As a result, the robustness of beamformer is improved. Simulation result shows that performance of proposed method is close to the existing method using diagonal loading in ideal condition and better than the latter when mismatch exists.