The invention discloses a foreign object identification method of a power transmission line based on Hoff linear transformation. The method comprises the following steps of carrying out gray-scale processing on a power transmission line image; carrying out median filtering processing on the power transmission line image after the gray-scale processing; using an Otsu method to carry out image segmentation so as to acquire a binary image to be identified, and then carrying out Canny edge detection; and after Hoff linear transformation is performed, using a characteristic that a foreign object is attached to a periphery of a power transmission line so as to carry out convolution operation on the power transmission line. By using the foreign object identification method of the power transmission line based on Hoff linear transformation, a foreign object identification result is good and a foreign object detection identification demand to a basic inspection tour image can be satisfied. The method is applied to transmission line inspection so that inspection tour manpower cost is effectively reduced and inspection tour efficiency and precision are increased. A great engineering application value is possessed and a new means is provided for power transmission line foreign object identification.