This paper analyzes and discusses the main problems of line detection and extraction by traditional Hough transform in detail. Thus, it proposes an algorithm of straight line extraction by Hough transform combining edge grouping. This algorithm first adopts an edge tracking based on eight-neighborhood to group the detected edge points by Canny operator. It then separately performs the Hough transform to each edge group obtained by grouping, and individually determines the origin of the Hough transform and the range of parameter. This algorithm uses the iterative vote scheme to determine the single peak and the corresponding points to be deleted. The experimental results prove that the proposed algorithm is simple in principle and can effectively solve problems in the traditional Hough transform, such as low precision and complex computation. The proposed algorithm has robustness, can process different content images, and is suitable for parallel processing.