Abstract: When directions of the interferences fluctuate and the desired signal steering vector mismatches, the conventional adaptive beamforming algorithms cannot effectively suppress the interferences continually, and it will cause null in the direction of the desired signal. In these cases, the performances of the conventional algorithms degrade severely. To solve this problem, a robust beamforming algorithm based on nulls optimization is proposed in this paper. In the proposed algorithm, the nulls of the interferences are firstly broaden by the rotation of the steering vector. Moreover, the sampled data is projected into the interference subspace. Then the interference component is weighted to enhance the powers so that the interference nulls are deepened. Finally, the uncertainty set constraint algorithm of the steering vector is applied to guarantee the gain of the desired signal. The computer simulation results show that the proposed algorithm can broaden the interference nulls effectively as well as guarantee the gain of the desired signal.