Abstract: In order to ensure high quality weathering steel welding, we introduce picosecond pulse laser cleaning technology into welded joint cleaning. This paper studied the effect of picosecond pulsed laser cleaning on stress corrosion resistance of SMA490BW weathering steel welded joints. X-ray residual stress test shown that: The residual stress on the surface of the specimens after laser cleaning increased 130 ~ 200 MPa, which was not conducive to the performance of stress corrosion. But, the cyclic corrosion test proved that: The corrosion resistance of the specimen surface has been improved by laser cleaning, which is helpful to the stress corrosion resistance of the joint. Finally, the three-point bending stress corrosion test proved that: Laser cleaning can improve the stress corrosion resistance of the weathering steel joint. The reason is that the laser cleaning makes the surface formed micron scale (0.8 ~ 1.2 μm) tightly packed columnar particles, which improved the corrosion resistance more than the influence of the residual tensile stress.