Abstract: A photosensitive epoxy acrylic resin suitable for UV-curing rapid prototyping was synthesized and the photo-solidification mechanism of the photosensitive resin was discussed.The microstructure of the solidified photosensitive resin was characterized by means of SEM and solidifying process of the photosensitive resin was analyzed by means of IR spectrometry.The results indicate that the microstructure of UV-cured photosensitive resin is irregular cross-link net form and in the photo-solidifying process of photosensitive resins,the content of photo-initiator in centain range is directly proportional to the inversion rate of C=C double bond.