A middle infrared and visible optical diagnostic system was designed for EAST Tokamak plasma. Through adopting innovate optical structure, the system satisfied the imaging requirements, and avoided the radiation and stain at the same time. And through using dichroic beam split mode, the middle infrared and visible path can image with common aperture and filed, which improved the observation efficiency. At last the wide-angle infrared and visible plasma imaging system was designed, with 3 mm aperture diameter and 58°×47° field of view. After alignment, the optical performance was tested, and the results show that all of the indexes satisfy the requirement the system. Through the imaging experiment for the discharge process in the EAST tokamak, the middle infrared and visible path of the system can image with wide-angle and high contrast synchronously.