The working principle of four-quadrant detector for laser guidance was introduced. According to the technical requirements of laser guidance and the working characteristics of four-quadrant detector, an improved method of lens design of four-quadrant detector for laser seeker was proposed. Aiming at the problem that nonlinear relationship was not easy to solve, the four-quadrant detector lens was designed by using Zemax in sequential mode, and the energy distribution of the light spot was controlled by setting operand, so that the angle deviation of the target was linearly related to the output signal of the four-quadrant detector, which could improve the real-time detection accuracy. The feasibility of this method was verified by simulation analysis combined with application background. The simulation results show that the full field of the system is ±10°, the linear field of view is ±0.8°, the focal length is 21 mm, the spot radius is about 0.4 mm, the pupil diameter is 36 mm, and the optical length is 35 mm. This method does not require uniform energy of light spots on the detector, nor does it require uniform size of light spots in each field of view, which greatly simplifies the design.