In the ground verification demonstration experiment of the space debris detection and ranging composite system, the working environment is 10-30 ℃, the size limit of the optical base station (not exceeding 450 mm×400 mm) and the installation of the tail of the optical telescope cause the center of gravity to be far away from the mounting surface. Design of optical telescope for space debris detection and ranging compound system was proposed. The finite element model of the optical telescope was established by using ANSYS finite element analysis software. The analysis was carried out under the conditions of ambient temperature of 10-30 ℃, tail installation, optical axis direction and vertical optical axis direction of 1 g (g = 9.8 m/s²) gravity acceleration. The analysis results show that the first-order mode of the optical telescope is 133 Hz and the dynamic stiffness is better. When the gravity is in the direction of the optical axis, the maximum change in the distance between the primary and secondary mirrors is 0.01 mm. When the gravity is perpendicular to the optical axis, the maximum distance between the primary and secondary mirrors is 0.007 mm. The RMS value of the wave aberration of the optical telescope system is λ/15, and the maximum inclination angle of the secondary mirror is 1.93″. It has good power and thermal stability and can meet the index requirements in the process of optical antenna installation, calibration, testing and field experiment verification. After the optical telescope is assembled and calibrated, the image quality of the optical telescope is tested using a ZYGO interferometer. The test is performed under the conditions of gravity perpendicular to the optical axis and ambient temperature of 10 ℃, 20 ℃, and 30 ℃. The results show that the RMS value of the system wave phase difference is respectively at 0.097λ, 0.075λ and 0.1λ, the RMS value of the wave phase difference of the whole optical telescope system is better than λ/10 at the lowest temperature and the highest temperature, and all meet the requirements of the system.