Abstract: The penetration butt welding experiment was carried out on the Dss2205/X65 bimerallic sheet by the fiber laser, The microstructure of weld metal was analyzed with optical microscope. The distribution of the alloying elements element in the welded joints were was analyzed by EDS. The potentiodynamic scanning method was carried out to measurement the anodic polarization curves of welded joints. The experimental results show that the microstrucure of the welded joint exhabits a hierarchical characteristics along thickness direction of welded joints. Polarization curves show that the joints with the welding speed of 1.2 m/min,1.5 m/min, 1.8 m/min showed an better corrosion resistance, and further rmore, With the increase of welding speed, the pitting corrosion resistance of joint is increased.