Abstract: Transmission line guyed tower is widely used in high-voltage transmission lines because of its reasonable stress and good economy. The tension monitoring of guy cable is considered as an important means to ensure the structural safety of guyed tower. In order to overcome the problems of poor stability, low accuracy and low efficiency of traditional tension measurement methods, this paper proposes that vibration images of guy cables under artificial or environmental excitation are collected by camera, and the guy cable area is accurately located based on edge detection and morphological operations. Then the edge fitting is carried out to obtain the vibration displacement time history data of the guy cable area. On this basis, the tension of drawing wire is calculated by a frequency-based method. The experiment and engineering application show that the maximum measurement error of the tension measurement method of transmission line guyed tower based on image edge recognition is less than 3%. The method has the advantage of non-contact, and has a good application prospect in the structural safety evaluation of transmission line guyed tower.