Abstract: In order to improve the strength of laser welding joints between metal and plastic, a method of microstructure laser welding of dissimilar materials was proposed. In order to explore the influence of surface microstructure parameters on the strength of metal and plastic laser welding joints, femtosecond laser was used. Microstructures with different parameters were prepared on the surface. The influence mechanism of microstructure parameters on the strength of welded joints was explored by means of tensile shear experiments, connection interface and cross-sectional microscopic observations. The joint strength is related to the filling effect of the microstructure and the connection area. As the size of the microstructure increases, the strength of the metal-plastic welded joint increases, but too large size of the microstructure will make it impossible for the molten plastic to fully fill the microstructure. The appearance of unfilled defects will reduce the strength of the welded joint. As the separation distance increases, the microstructure coverage decreases, the effective connection area between metal and plastic decreases, and the strength of welded joints continues to decrease.