In order to improve the recognition accuracy of medium and long distance vehicle targets and meet the requirements of the forward preview distance of pilotless automobile, a type of medium and long distance automotive lens suitable for passenger cars is studied through theoretical calculation and optical design software ZEMAX-EE. To meet the requirements of the imaging range of the vehicle lens during actual use, the imaging range with different entrance pupil diameters is calculated by using the depth of field formula, when the aiming distance is infinity. Then the lens parameter design scheme which satisfies actual service conditions is determined, and it is easy to design and test. For the automotive lens, the focal length is 40 mm, the field of view is 8.6°, the entrance pupil diameter is 7 mm, the depth of field is 30 m-+∞, and the system total length is less than 38 mm. The simulation results show that the designed lens has good image quality and can meet the design requirements in actual use.