Direct tooling using stereolithography (SL) photopolymer has been developed as rapid tooling for short-run injection molds. However, the tool strength, thermal conductivity, and erosion resistance of SL mold are lower than that of the conventional metal mold. Previous study has showed that the tool life was limited under 200 shots and tool damage often occurs during part ejection. In this paper, experimental data from a demolding properties test are presented and discussed. The experiments were performed using various cooling time, hold pressure, and mold temperature. The experimental data were analyzed by measuring demolding force and surface roughness to evaluate tool life and failure mechanism in order to obtain a working range for the process parameters. The test result shows that the demolding force has close relation with cooling time and mold temperature.