Air temperature is one of the main meteorological parameters that affect the electrical distance and mechanical strength of overhead transmission lines. Given the need for real-time operation state safety monitoring of overhead transmission lines, a method of spatial shape simulation and accuracy verification of the lines under environmental temperature changes is proposed. It is based on airborne LiDAR point cloud. First, the spatial model of a transmission line is constructed using point cloud, and the horizontal stress of the transmission line at the initial temperature is extracted. Then, the horizontal stress of the line under simulated temperatures is solved according to the state equation. Finally, the spatial shape simulation of a transmission line is realized according to the principle of static balance. A two-phase cross validation method of excitation point cloud is proposed to verify the reliability and accuracy of the simulation results. The typical point cloud data of transmission lines are selected for test. The results show that the method can well simulate the spatial shape of overhead transmission lines under any temperature change environment. The simulation error is 0.027, the average error is 0.066 m, and the maximum error is 0.471 m. The research provides reference value for airborne LiDAR power inspection and high voltage transmission line design. This work is supported by the National Natural Science Foundation of China for the “Natural Forests Biomass Estimation at Tree Level in Northwest Yunnan by Combining ULS and TLS Cloud Points Data” (No. 41961060).