Abstract: With shear tension and fatigue strength tests on penetration and non-penetration stainless steel laser welding head and resistance welding head that are used in rail train tests and a preliminary analysis of the microstructure and fracture mechanics, which fatigue tests use the staircase method and group method. It can concludd that non-penetration laser welding stainless steel body has higher fatigue strength than penetration laser welding and resistance spot welding. And under the same laser welding parameters it could directly affect craft shear and fatigue strength when changing the non-penetration plate's thickness of the non-penetration laser welding craft.