A non-contact measurement system based on high-speed camera is designed for deformation measurement of flexible hydrofoil in oscillating hydrofoil tidal current power generation device, which can continuously collect images and calculate hydrofoil deformation without affecting hydrofoil hydrodynamic characteristics. The coordinate transformation model of image coordinate system and hydrofoil world coordinate system is established, and the calibration method of relevant parameters and the formula of deformation calculation are given. A new method of edge detection of the upstream surface of hydrofoil based on Canny operator is proposed and the polynomial fitting formula of the boundary is given. In this way the deformation of any point on the edge of the upstream surface of the wing can be calculated. Different experimental conditions are set to verify the results. The total length error of the identified hydrofoil is less than 2%, and the deformation is in line with the actual law. The experimental results show that the method can effectively measure the deformation of any point on the edge of the upstream surface of the hydrofoil, and has the advantages of simple field arrangement and no influence on the hydrodynamic characteristics.