It is imperative to increase the service reliability of the laser welding dual phase (DP) steel joints for an auto-body which are subjected to dynamic loading during their manufacturing processes, as well as in an accident. Laser butt welding of DP600 is performed by using a pulsed NdYAG laser. Microstructures of the welding joints are analyzed. Microhardness and mechanical properties at various strain rates of the welding joints are tested. The results show that welds with good appearance can be obtained under the proper welding conditions. The microstructure of weld zone (WZ) is mainly martensite, and the microhardness is higher than that of base metal. And the heat affected zone (HAZ) is narrow, and there exists HAZ softening that occurs in welding because of the tempering of the martensite phase. The mechanical property of the DP600 welding joint is sensitive to the strain rates. After welding, the yield and tensile strength of DP600 increase as the strain rate increases, while the fracture elongations are all lower than that of the base metal. All tensile fracture of DP600 welding joints are typical ductile fracture characterized by dimples at various strain rates ranging from 10-3 to 103 s-1.