The invention discloses a method for calculating a dangerous point of a transmission line based on laser point cloud radar data, which comprises the following steps: collecting laser point cloud radardata and performing data preprocessing; automatic classification of the pre-processed point cloud data; the power line point cloud data being segmented according to the length of each segment by 1 meter, and the middle point of each segment being taken as the characteristic point; building Octree Index in Non-Power Line Point Cloud Data; setting a safety distance, the safety distance comprising ahorizontal distance, a vertical distance and a clearance distance; taking the characteristic points as the searching points, the nearest neighbors within the radius of the non-power line point clouddata being searched to find out the dangerous points. The invention solves the technical problems that the prior art calculates the dangerous point of a transmission line, collects data by a worker onthe spot, judges artificially by naked eyes or experience, and cannot accurately obtain the distance between the dangerous point and the transmission line, the operation efficiency is not high, the human cost is large, and the real-time property is not strong, etc.