The invention provides a method is for recognizing rain-wind induced vibration waterline of a stayed cable based on computer vision. The method is characterized in that non-contact measurement is realized for evolution of the form of the waterline through an image recognition algorithm. With the method, a measurement region is arranged on the surface of the stayed cable, a coordinate grid system is drawn, the movement pictures of the waterline in the measurement region are shot through a high-speed CCD camera, and first, according to color difference contrasting, the water line is recognized from an original picture; then through grayscale correction and a gray threshold method, a binary image of the coordinate grid system is obtained, and all coordinate lines are expressed through equations based on Hough conversion and least square fit; finally, the distribution position of the waterline on the surface of the cable is determined through the coordinate grid system. With the method, the movement pictures of the waterline shot constantly are recognized, and then the evolution process of the form of the waterline can be reconstructed. The method has the advantages of being wide in measurement range, obtaining much waterline information and being high in precision, and a device is simple, convenient and rapid to operate and easy to transplant to application of actual bridge engineering.