To meet the needs of further miniaturization and cost reduction for existing immersive flying simulator, a spherical zone projection lens for small and medium-sized flight simulator was designed. The key parameters of each component (spherical zone, projector, projection lens) in the projection scheme was determined. The designed lens has a field of 172° and inverted-telephoto ratio of 6:1, put a projector with the designed lens on the screen, and the whole screen would be fully projected. The construction method of optical system with large field of view and inverted-telephoto ratio was provided, the distortion, field curvature and relative illumination in large field nonsimilar imaging systems were analyzed and discussed, and the effective method of improving the illumination uniformity was also presented. The proposed lens meets the high-quality projection requirements of 4 k resolution with a low-cost structure of 8-piece lens, and its MTF values of all the fields are higher than 0.4 at the nyquist frequency of 185 lp/mm, which has good workability.