Regular hexagon is a kind of common geometric figure. This paper proposes a vision detection method based on geometric characteristics to detect regular hexagon. First, line segments are detected in the image by hough transform. The line equations are constructed according to the detected line segments in the image space. Second, the line equations are utilized to compute the intersection points of adjacent two lines. The lengths of every side of regular hexagon are gotten by computing the distances between adjacent two intersection points. The angles between adjacent lines are calculated. Then the circle detection method based hough transform is employed to inspect whether all intersection points locate at the same circumference. Finally, the detection experiment of hexagon bolt is constructed to illustrate the performance of the presented method. The measurement errors of angles between adjacent two sides and lengths of sides of regular hexagon are 0.38% and 0.85% respectively. The result shows that the presented method is effective and can precisely detect regular hexagon in the image.