Performance of recoating system is a key factor influencing building accuracy and fabricating resolution of stereolithography (SL) system. In order to obtain thinner resin layer, a piston recoating system was adopted in high-resolution SL system. To improve the recoating performance of piston recoating system, studies were carried out to investigate the influences of recoating parameters on thickness of recoating layer, and a mathematic model of resin layer thickness has been established. Experiments results show that thickness of resin layer increases with the gap between blade and object, and thickness of resin layer increases with the resin volume added into the vat during recoating. Experiments results also indicate that thickness of resin layer decreases with blade speed and blade thickness. The research provides a basis for optimizing the recoating parameters for the piston recoating system.