Monopulse radar is widely used for its accurate angle measurement. However, when jamming occurs, especially in mainlobe, the performance of the monopulse technique for target estimation deteriorates greatly. In this paper, an improved method for monopulse angular tracking is proposed, which can be divided into two stages. The first one involves a digital beamforming system which is used to suppress sidelobe jamming while maintaining the mainlobe shape. The second stage is used to suppress mainlobe jamming while maintaining the monopulse ratio undistorted. The computation load of the proposed method is lower compared with that of the same category method. Simulation results are given which demonstrate that the presented approach can suppress jamming effectively, while maintaining the perfect performance with mainlobe undistorted.