A method for improving the quality of rapeseed image segmentation based on the gradient improvement of Hough transform is proposed. At first, the original image is converted to gray image, then the center of rapeseed is found by the improved Hough transform, the connecting line of the center of the two adjacent rapeseed is found, and the tangent that perpendicular to the connecting line of the center is considered to be the boundary between the two rapeseed to separate it. Compared the segmenting effects of the same image, the result by above method is superior to those by some common image segmentation methods.