In precision machining, we often detect the location of some round holes or other geometric parameters. Given the disadvantages of traditional method is contacted, artificial and time-consuming, this paper has proposed a image measurement method based on stereo vision. We use the method of digital image processing to perform the denoising, binarization, edge detection, and centralized location of the orifice image, and analyze the accuracy of the hole machining and arrangement. Experimental results show that the error of image measurement proposed is less than 0.14mm, which meets the general requirements of the hole measurement precision and is applicable to the online measurement that the accuracy requirement is not high and the task with large amount of object to detect.