Abstract: As a camera lens for intraoral camera system, GRIN (gradient refractive index lens) lens has many merits such as light weight, simple structure, small volume and big focal depth. A heat treatment method is put forward to improve the quality of GRIN lens. The boundary conditions are modified to control the refractive index profile in heat diffusion. GRIN lens can be used to achieve the image for oral cavity and the images are transformed to electrical signals by CCD, then electrical signals are converted into digital signals, stored in computer and displayed on monitor.