To solve the computation complexity and robust problems of conventional space-time wideband beamformer structure, a low complexity robust algorithm is proposed. Firstly, the array response phase when the frequency changes is given, and the influence of frequency change and angle change on the phase of array response are analyzed. Through imposing magnitude and phase constraints to compensate the phase differences between different frequencies for desired signal, robust wideband beamforming is achieved without delay lines or FIR/IIR filter. Furthermore, by analyzing the impact on array response phase when the frequency and angle change simultaneously, the auxiliary azimuth in the vicinity of desired signal is taken into account, and the robustness of the algorithm is improved when the arrival direction of the desired signal tends to zero and the relative bandwidth is small. The theoretical analysis and simulations show that the algorithm has simpler structure, lower computational complexity, and better robustness than traditional algorithm.