Abstract: In order to solve the problem that the alignment calibration method of aiming at stars in naval gun weapon system is easily influenced by the weather, an optical alignment calibration method with need of reference object for the integrated weapon system of radar (photoelectricity) and naval gun is proposed. The gun barrel axis is led out by the laser beam and translated parallel to the radar (photoelectricity) receiving window through the alignment optical module, then the angle difference between the radar axis and barrel gun axis is obtained to be calibrated. Test and experiment results show that the method is characterized by simple operation, high efficiency and real time, it has the alignment calibration error no more than 0.5mrad. This method is impacted less by the weather and environment conditions compared with the method of aiming at stars, and has a significant role to give full play to the operational effectiveness of gun weapon system.