In order to develop high quality and efficient welding technology which is suitable for layered bimetallic sheets, based on the Marangoni convection behavior of molten pool in full penetration welding processes, the dissimilar metals co-pool single pass laser butt welding of bimetallic sheets was presented, and the welding of X65/DSS2205 bimetallic sheet was implemented. Metallographic observations indicated that upper and lower welding seam has obvious characteristics of independent metallographic formation, and there are no indecisive boundaries between the two metallographic formations. The EDS results show that under the optimum process conditions (by orthogonal test), the retention rate of alloying elements such as Cr, Ni and Mo were near 97%.