In order to solve the problems of large distortion, large size, and low energy utilization of the projection system, a new small distortion projection system based on the double Gaussian structure and freeform surface lighting system is designed. The optical system is designed mainly for the freeform surface modeling method and optical path structure. According to the edge ray theory and Snell's law, a numerical iterative method is used to design the freeform surface lighting system. The simulation results show that the illumination uniformity of the lighting system can reach 87.86%, and the energy utilization rate can reach 94.38%. The imaging system is designed with a double Gaussian structure as the initial structure. The distortion of the projection system after aspheric optimization is 0.26%, and the optical transfer function is greater than 0.8 at a frequency of 93 pl/mm, and greater than at the 35° edge field of view 0.6. The imaging quality of the projection system is high, the structure is compact, and the number of lenses is small. Through the tolerance analysis, it can be known that the Q5 tolerance level meets the performance requirements of the system, and the tolerance requirements are relatively low.