Abstract: A robust wideband constant beamwidth beamforming algorithm is proposed to solve the problem of performance degrade of traditional wideband beamforminers when there exists direction of arrival (DOA) estimation error. Beam response at the look direction and nulling is imposed by selecting discrete point at the range of DOA angles. With the spatial response variation constrain, the response at different frequencies can be simplified as a reference frequency. Then the beamformer can be obtained combining with the norm constraint of the weight vector. Finally, the optimal weight can be solved with the methods of interior-point and Lagrangian. Experiments illustrate that the algorithm gets an available spatial filter result for moving targets, and achieves a preferable constant beamwidth performance and a high output signal to interference plus noise ratio.