Abstract: The laser welding test of 10 mm thick 316L austenitic stainless steel with nitrogen shield was carried out by high-power fiber laser in order to reduce pores. It is found that the porosity decreases significantly with nitrogen as shield gas than argon as shield gas, and that the weld section is narrower. The excellent "keyhole" welding joint is obtained. The width of the weld surface is about 2 mm; the width of the weld root about 1.5 mm. The weld face is slightly concave, and the depth-width ration is 5∶1. The results of RT and PT meet the requirements of NB/T 47013—2015 GradeⅠ. The results of mechanical and technological properties meet the requirements of NB/T 47014—2011. The impact performance test shows that the weld has excellent impact performance. The impact fracture is observed by microscopy, and the dimples are obvious, which is a typical ductile fracture. The weld zone is mainly dendritic austenite and precipitated phase, and the HAZ is mainly twinning austenite and δ-ferrite.