The scheme of emitting lens direct collimating semiconductor laser source can make the linear scanning lidar more compact and cheaper, but the high power semiconductor laser source heating seriously will lead to the thermal deformation of optical elements, which will lead to the sharp reduction of the optical power received by the detector and make it undetectable. A thermal integration optimization design method for the optical path of line-scanning laser radar with a detection range of 30 meters is proposed. This method firstly takes the preset working temperature from 40~80℃ as the initial condition, and optimizes the optical path system of the transmitting lens and receiving lens based on Zemax software, so that the optical performance of the optical path system operating at 60℃ is the best. Secondly, the finite element method was used to analyze the thermal deformation of optical elements when the optical path and the corresponding mechanical structure changed with temperature, and the mechanical structure of the optical path system was optimized by adding SiO2 aerogel as thermal insulation material. Machine heat integration optimization results show that the optimization design method, the optimized optical path and mechanical structure in the working temperature of 40~80℃ range detector receives the light power in 10-4w level all the time, compared with only using Zemax software optimization design method of emission and receiving lens (detector receives the light power 10-6~ 10-4w) has significant improvement.