A method for identifying and extracting a linear object from an image is disclosed. The method comprises: acquiring an original image to be processed, wherein the original image is taken by a camera, received through network transmission or copied from a compact disc or a removable disk; preprocessing the original image to obtain an enhanced image; extracting an edge information image from the enhanced image; then extracting linear features by performing, on the edge information image, a linear feature extracting transform improved with a cluster operator; finally; identifying and extracting the linear object by distinguishing the linear object from other linear features by considering characteristics of the linear object to be identified and extracted. According to the invention, a linear feature extracting transform improved with a cluster operator is constructed from a distribution of edge pixels in the edge information image along a 2-dimensional direction, which makes it possible to extract, rapidly and accurately, weak linear objects such as power lines from images having complicated background and sub-pixels.