Abstract: To improve the imaging quality of the lens used in helmet-mounted low-levellight (LLL) night vision system and make the lens light in weight, small in size, compact in structure, a high order aspheric lens is designed. According to the theoretical calculation of the lens parameters specific to the helmet-mounted LLL night-vision system, lens parameters are designed to meet the demand. With the high order aspheric lens designed, the number of lenses in object lens is reduced from 9 to 6 and the number of lenses in ocular is reduced from 9 to 7. The analysis results show that the configuration of the aspheric surface for helmet-mounted LLL night-vision systems can make its lens configuration simple.