A curved surface measurement method based on monocular vision system is proposed to measure the curved surface of the special-shaped parts. First, the monochromatic vision system which is composed of a tricolor LED ring structure light source and a three-color CCD color camera is used to collect a single color image that contains the surface characteristics of the measured surface. Secondly, the correlation of color distribution features of the images, the regular of gray level variation and characteristics of adjacent regions are analyzed, and the segmentation method is designed to complete the target surface segmentation. Then, the calculation equation of the measured surface height is derived based on the image model of the monocular vision system and the related parameters of the material and the experimental environment. Finally, the height of the measured points is reduced by solving the height accumulation component between adjacent pixels. On this basis, the surface curvature measurement model is established and the curved surface is measured. The surface curvature measurement experiments respectively for 3D printing surface samples, screw thread and SIM card slot are carried out based on the proposed method. Comparing with the laser triangulation measurement method results, it shows that the errors are all less than 3.6%, the measurement accuracy is 0.000 1 rad, and the time length of measuring is less than 0.6 s. The experimental results show that the proposed method has good adaptability for measuring object edge, height abrupt change, height gradual change and other types of surface. It can achieve high precision measurement and fast measurement speed.