In view of the problems that existing contact measurement methods can only measure one or two parameters after clamping and positioning， and low inspection efficiency， and combining the machine vision inspection technology has outstanding advantages such as no contact， no damage， high degree of automation and safety and reliability， a geometric errors vision inspection method of the air rudder was proposed. Firstly， the images of rudder shaft and rudder surface area were acquired by a computer vision system， and image distortion was removed using the camera parameters and distortion parameters obtained from the camera calibration. Image pre-processing techniques were used to remove noise and reduce the impact of non-target elements in the detection environment on the detected object. In order to extract the rudder-like structural member edges more efficiently， Sobel operator， Scharr operator， Laplace operator and Canny operator were used to detect the edges of the image to determine the contours.In order to more effectively extract the edge and determine the contours of the air rudder， the Sobel operator， Scharr operator， Laplace operator， and Canny operator were used to detect the edge detection of images. The experimental results show that the edges of the rudder shaft image were sharper and more complete after the Scharr operator， and the edges of the rocker image were sharper after the Canny operator. Therefore， the Scharr operator was used to extract the edges of the rudder image and the Canny operator to extract the edges of the rocker image. Combining the characteristics of the testing elements， Hoff straight line and Hoff circle detection methods are used to extract rudder surface edge line features， rudder shaft bus features， and rocker arm circle contour features. And the reference elements of the rudder core symmetry， rudder shaft perpendicularity， and rocker arm pinch angle are determined. Construct an objective function for geometric quantity error detection and compute the optimal solution using an adaptive genetic algorithm. The measured values of rudder core symmetry， rudder axis perpendicularity and rocker angle are obtained from the internal and external reference matrix obtained from the camera calibration. Finally， the vision inspection software for geometric and assembly errors of air rudder parts has been developed， and the vision inspection experiment platform has been constructed to realize the rapid detection of geometric and assembly angle errors of air rudder parts. After several repetitive measurement experiments， the symmetry inspection accuracy reaches 0.086 mm， the perpendicularity inspection accuracy reaches 0.233 mm and the assembly angle inspection accuracy reaches 0.373°， and the detection time is 7 s.The experimental results show that the method not only improves the accuracy and efficiency of geometric errors detection， but also helps to improve the automation and intelligence of forming-manufacturing-in-machine inspection of air rudder parts.