In order to understand the influence of process parameters and shape parameters on the forming accuracy of laser selective melting parts, a mathematical model was established for the dimension error in height direction and the shape error of arc surface.The orthogonal experiment of laser selective melting was carried out with 316L powder on the basis of printing layer thickness of 200 μm，five factors and four levels including laser filling power, laser contour power, scanning speed, shape parameters and scanning distance were selected for the experiment. The experimental results show that the influence factor of surface roughness is laser power, and the roughness value decreases with the increase of laser power；the influence factors of profile error are shape parameters and filling laser power. There is the worst center angle, and the profile error increases with the increase of laser power. The influence factor of dimension error in height direction is mainly the structure of the part itself, and the influence of processing technology on dimension error is not significant. This study provides a theoretical and experimental basis for the accuracy analysis of laser selective melting 316 parts.