This study makes use of CAE software to establish a multiphysics field model concerning the flow, solidification, and heat transfer processes of laser-selected 316L stainless steel powder melt pools. The research aims to examine the morphology evolution of the melt pool and analyze the impact of variable process parameters on melt pool morphology, thermal field, and flow field. It was found that the peak temperature at the observation point of the melt pool, the maximum flow rate of the melt pool, the melt width, the melt depth and the laser energy absorbed by the powder increased with the increase of laser power at the scanning speed of 600 mm/s, and decreased with the increase of scanning speed at the laser power of 110 W. During the evolution of the melt pool (P=180 W, v=800 mm/s), when t=0.05 ms, the shape of the melt pool is approximately circular; when t=0.30 ms, the shape of the melt pool changes from circular to elliptical, and the temperature of the melt pool remains stable, after which, the shape of the central part of the melt pool is always approximately elliptical; when t=0.65 ms, the depth of the melt pool gradually increases, and the solidification speed When t=1.0 ms, the temperature of the melt pool gradually decreases, and the temperature is lower than the solid-phase line temperature 1 658 K when the melt channel is formed. Under conditions of a 600 mm/s scanning speed and 110 W laser power, the resulting melt channel demonstrates relative continuity and smoothness, reflecting good quality.