During stereolithography processes, one of the main sources of dimensional error of prototype is the distortion effect owing to the shrinkage of resin. In this study, the effects of dimension of specimen, such as length, width, and thickness, on the curl distortion is examined. During the SL processes, the variation of curl distortion ewer is measured according to the number of layers, Through this study, it is verified that there is a big difference of the distortion error in both direction and magnitude between before and after the supports are removed. It Is also observed that end profile of the test part and the upper side around the border are also distorted due to the shrinkage of the resin.