In order to realize the light-weight and miniaturization of the remote laser ranging system,a large-aperture Cassegrain objective optical system was adopted,and a field-of-view aperture matching the field of view was added to suppress the influence of stray light on the detection capability.Through reasonable optimization of the layout,the system horizontal dimension and the shielding ratio of primary and secondary mirrors are balanced.Finally,a structure of 8× telephoto system combined with a large relative aperture focusing system is adopted.The optimized system has good image quality,high energy concentration,compact structure and light weight,which can meet the practical application requirements.