The invention discloses a power transmission equipment fault diagnosis method. The method comprises the following steps: A) establishing a normal image database of power transmission network equipment, wherein the power transmission network equipment comprises power transmission lines, fittings and insulators; B) collecting operation images of the power transmission network equipment, and carrying out pretreatment and image feature extraction on the collected operation images of the power transmission network equipment; and C) through an image comparison module, by utilizing the collected operation images of the power transmission network equipment and images in the normal image database of the power transmission network equipment, analyzing change and defect characteristics of the power transmission network equipment in the operation images of the power transmission network equipment, and image difference in the normal image database of the power transmission network equipment under normal state of the equipment, and carrying out fault identification and diagnosis on the power transmission equipment. The method can find possible fault hidden trouble of the power transmission lines in time through a structure template analysis and defect feature pattern matching combined method, thereby greatly reducing fault judgment error.