A three dimensional geometric model of a homemade selective laser sintering (SLS) system is simplified and imported into Ansys Finite Element Software for static and modal analysis. The analysis results show that the supporting base that holds up the laser system undergoes large deformations. The machining accuracy can hardly meet the high-precision requirements of sintered parts with complex internal and external geometries. A method is put forward for the structural optimization of the SLS system. The calculation results show that the bending deformation of the supporting base decreases by 73.2%, and the maximum stress also decreases significantly. It indicates that the high precision manufacturing can be achieved with the improved SLS system.