A fast parameter measurement system based on machine vision was put forward to against the problem existing in the surveying engineering of cycloidal gear. Firstly, the structure and function of the hardware and software systems were introduced. Then, the image information was processed by using OpenCV function lib to achieve the gear outline, and edge coordinates was extracted by using contour search technology. At last, based on the definition and measurement principle of cycloidal parameters, cycloidal gear parameters and errors were measured. The test result shows that the measuring system can meet the need of measurement error, and the measurement efficiency is improved. It provides a new thinking and platform.