Abstract: In this paper, the cavitation erosion behavior of 316L welded joints at different heat input in the liquid lead bismuth alloy was studied. After the cavitation corrosion test for 80 hours, the surface morphology and roughness of the samples were analyzed by electron scanning electron microscopy (SEM) and atomic force microscopy (AFM). Research showed the cavitation erosion resistance of 316L welded joints in liquid Pb-Bi depends on the austenite grain size. As welding heat input increases, the austenite grain size becomes larger, which leads to the poor corrosion resistance. The cavitation erosion resistance of 316L base metal is better than that of welded joints at the same cavitation erosion time.