The present invention provides an unmanned aerial vehicle-to-power transmission line spatial distance measuring method and apparatus and belongs to the unmanned aerial vehicle technical field. The method includes the following steps that: a spatial distance from an unmanned aerial vehicle to a power transmission line is acquired; position information is obtained, whether the position information reaches a preset clearance value is judged; if the position information reaches the preset clearance value, direction information and laser information are acquired; the position information, the direction information and the laser information are processed, so that point cloud data can be generated; the point cloud data are spliced, so that the position information of an obstacle can be obtained; and if the position information does not reach the preset clearance value, an early warning device is triggered to given an alarm. With the method adopted, the spatial distance from the unmanned aerial vehicle to the power transmission line can be accurately measured, the obstacle can be identified, and line inspection and distance measurement can be more efficient and faster.