Abstract: With the development of laser radar technology and the improvement of ranging accuracy requirements, the new requirements are put forward for the transmitting and receiving optical system, which should have the characteristics of adjustable beam, small measurement spot and high echo efficiency. An transceiver integrated optical system working in the optical communication band of 1 550 nm was designed. The transmitting and receiving modules share part of the optical paths to reduce the receiving blind area and facilitate the miniaturization of the structure. In order to solve the problem of echo energy difference caused by different measurement distances and different surface inclinations, the beam expansion components of the optical system were made into a continuously adjustable structure with the magnification of 2~3.5 times. The two sets of double gluing lenses were used for chromatic aberration correction to reduce the influence of spectral width on the system propagation distance. After design optimization, the laser divergence angle after system collimation is less than 0.3 mrad, and the diameter of the emergent light spot is continuously adjustable from 6.26 mm to 10.20 mm. For the measurement targets within 50 m, the diameter of the irradiation light spot is less than 20 mm, and the divergence angle as well as the light spot diameter meets the above requirements at different zoom positions.