Selective laser sintering technology is not limited by the shape of the parts, and can form parts with complex structures. Selective laser sintering technology is widely used in rapid prototyping manufacturing and new product design and development. It is particularly important to explore the dimensional accuracy of its forming. Aiming at the problem of low dimensional accuracy and shape accuracy of thin-walled shell parts, this paper proposes a method of preprocessing and precompensation based on part features to improve printing accuracy. Taking polystyrene as raw material, under the combination of simulation and experiment, in order to compensate the deformation, the method of adding support and offset margin is used to correct the feature size, which is easy to warp and deform, and the laser parameters are adjusted to improve the heat accumulation in the printing process. By verifying the printing results, the results show that under the same process conditions, the change of the geometric features of the part directly affects the dimensional accuracy of the part. After adding support settings and predeformation compensation to the part features, the printed parts are compared with the 3D model with good detection results, and the actual error can basically be controlled within 0.3 mm.