The large field of view coronagraph is used to image the corona within 215 solar radii. This coronagraph can be used to monitor the solar activity and forecast the violent space weather events. For the need of the stray light suppression, the coronagraph is designed to be an external occulted and secondary imaging system. The optical system has a length of 355.89 mm, a field of view of ± 20° and a focal length of 40 mm. The stray light of the coronagraph is divided into three levels by the intensity. The first level is the direct light from the sun. The second level is the diffracted light from the occulter and external diaphragm. The third level is the reflected light from the inner occulter, the diffracted light from the objective aperture and the scatted light. The three levels of stray light are suppressed respectively. Finally, the stray light level of the coronagraph is 10-9 at the inner field and 10-13 at the outer field.