In order to improve the low strength and precision of selected laser sintering of polystyrene (PS) powder, the PS/PMMA composite powder was prepared by adding PMMA powder. Taking dimensional accuracy and tensile strength of the workpiece as indexes, orthogonal experiments were carried out by selecting layer thickness, scanning speed, laser power and scanning distance. The range analysis was used to optimize the forming process and study the performance. The results show that the optimal process parameters for selecting the size accuracy of PS/PMMA composite powder sintering are preheating temperature 101 ℃, scanning speed 4 m/s, laser power 20 W, hatch spacing 0.25 mm, and layer thickness 0.24 mm. The X, Y and Z dimensional accuracy of PS/PMMA composite powder sintering can reach 0.004, 0.033, and 0.020, respectively. Through mechanical properties analysis, selected laser sintering PS/PMMA can improve the strength of SLS specimen, and the tensile strength is increased by 2.4% compared with PS sintered parts.