Abstract: Transmission lines' live working is one of the effective means to ensure the reliable operation of the lines. In order to solve the unsafe problems existing in the implementation of traditional live working. Grounded LIDAR is used to collect point cloud data, and a tile based on the pyramid data structure is employed to complete the storage and calling of the data. The improved bidirectional filtering algorithm is used to quickly distinguish surface features and obtain a 3D model of the site. Considering the characteristics of live working, data reading and query speed, the nearest point search algorithm based on octree is used to calculate the safety distance of each point in the planned path in real time, and the safety of the operation mode is obtained by comparing with the value specified in the regulation, and assist decision-making of the implementation plan. The actual working condition simulation is carried out by taking "the hanging basket swing method" as an example. The experimental results show that the established 3D model can meet the whole process control of the operation, and has achieved practical effect.