Abstract: The hot-dip Al-Si coated 22MnB5 steel plate was welded by laser welding at different welding speeds（70-110 mm/s） after 950 ℃ high temperature heat treatment, and the microstructure and mechanical properties of the welded joints were studied. The results show that since the cooling speed of laser welding is very fast, the microstructure of the weld fusion zone is mainly consist of lathy martensite, bainite and Fe₃（Al,Si） phase formed by the Al-Si coating melting into the fusion zone. With the increase of welding speed in 70-100 mm/s, the heat input decreases, the cooling speed increases, the martensite is refined, the content of Al in fusion zone decreases, the Fe₃（Al,Si） phase decreases, and the hardness, tensile strength and elongation of the welded joint increase generally. When the welding speed is 110 mm/s,the welded joint has micro crack defects due to incomplete penetration and its mechanical properties are reduced.