In order to improve the operational effectiveness of the laser weapon system, an automatic laser beam-combining device was designed based on the deflection mirror by analyzing the current situation of laser beam-combining technologies. Tests were made on the focusing, beam-combining and damaging effectiveness of two lasers. The results indicated that this method can achieve the expected focusing effects and beam-combining performance. Compared with the single high-energy laser, the time for damaging UAVs by two lasers combined beam is reduced by 58%. It provides a basis for multi-laser beam-combining research in the future.