The invention discloses a method for accurately identifying a power transmission line in real time. The method has innovations on two aspects of a new Radon conversion integral formula and a Radon conversion search method based on a boundary strategy. The new Radon conversion integral formula in the method can replace a conventional target enhancement process, the value of Radon integral conversion in a background part is inhibited through symmetry of partial derivative function values, and a power transmission line part is reserved. While the new Radon conversion integral formula is provided, Radon conversion is started from the boundary of an image according to application demands, and a search region is limited through a boundary selection mode, so that the purpose of shortening calculation time is achieved. A symmetric distribution rule of partial derivative functions of a natural image in the method is firstly discovered in a project, and related researches on the symmetric distribution rule are not found home and abroad. Through theoretical research and experimental verification, power transmission lines in various complicated aerial images can be effectively identified in real time.