Abstract: This article briefly describes the various components of the airborne light detection and ranging system, and analyzes error factors of the system. According to the Mianyang-Chengdu-Leshan inter-city railway station line engineering data of different base stations, we have differential treatment of the airborne GPS (global positioning system). Detailed comparative analysis of the forward/reverse separation mean value/distribution and photo positional accuracy of the calculated flight trajectories is performed. Finally we arrive at the ground base station layout scheme to improve data accuracy.