An oral cavity endoscope was designed to meet the practical needs of dentistry. The whole system was composed of imaging system, illuminating system, image display and processing system. The system has the function of micro-amplification, and the brightness and color temperature is adjustable. In this paper, optics software was used to design and optimize the optics imaging system, and gave out the aberration curve. The illumination system was constructed. In the ending of the papers, the oral cavity endoscope was used to test two teeth model. The system resolution is higher than 100 lp/mm and the image is clear. The details of tooth surface can be observed. The experiment results show that the system could meet the requirements of dental medical application.