This application pertains to the technical field of LiDAR, and discloses a receiving optical system, a laser receiving module, a LiDAR, and an optical adjustment method. The receiving optical system includes an optical receiving module and a first cylindrical lens. The optical receiving module is configured to receive a reflected laser and focus the received reflected laser. The first cylindrical lens is configured to receive the focused reflected laser and adjust the reflected laser in a first direction. Therefore, the receiving optical system can better perform matching on the photosensitive surface of the receiving sensor, and the energy receiving efficiency of the system is relatively high.