In order to meet the needs in thigh-reflecting copper welding and metal 3-D printing in aerospace and new energy vehicle battery manufacturing, a 500 W blue semiconductor laser module based on four 150 W array blue light units was developed by using spatial beam combining and polarization beam combining methods. Spatial beam combining technology has been used to independently compress the spot on the fast and slow axis to eliminate luminescent dead zone. Using polarization beam combining technique, we can successfully combine 4 independent light-emitting arrays into one single beam, increasing power density without deteriorating the beam quality or the divergence angle. In addition, a specific water-cooling system for the blue laser module was designed to meet the stability working condition for various industrial applications. Finally, thanks to the method above with the beam combining efficiency of 81.3%, a 501 W output with power fluctuations less than 0.7%, a fast (slow)-axis divergence angle of 0.4° (0.02°) has been obtained. In the follow-up research, one may expect the development of 4 kW-level high-power blue semiconductor lasers with coupled in optical fiber for output.