A measurement method was proposed for rotation axes of five axis machine tool based on machine vision. Firstly, the vision technology was adopted to obtain sign images by using CCD camera. Then, the digital image processing techniques were used to analyze these images. At last, the positioning errors of rotary axes were identified by calculating the relative rotary errors at different positions of rotation axes of machine tool. Comparing to traditional method, the experimental results showed that the proposed method with a simply, high efficiency and application value provided a computation basis for the error compensation of a machine tool.