Abstract: The dissimilar material butt welding tests between the B1400HS with Al Si coating after hot stamping and DP1180 steel were carried out by laser fusion welding with different welding speeds. The microstructure, hardness, and mechanical properties of the joints were observed and measured. The results show that with the parameter in this paper, the joints with good appearance can be obtained. In the weld, the main phase is martensite, and a few Al-rich phase exists on surface at the side of B1400HS steel. The structure of B1400HS HAZ is mainly martersite and tempered martensite, the HAZ has softening zone and the hardness is about 65% of the base metal. The structure of DP1180 HAZ is martersite, ferrite and tempered martensite, the HAZ also has softening zone, which is about 79% of the base metal. The heat input has little influence on the joint performance. The tensile test and Erichsen test specimens all fracture at B1400HS HAZ. The tensile strength is good, close to 1200MPa, but the elongation and Erichsen value of the joints are lower than that of the baste metals.