Aiming at the existing problems in line detection by standard Hough transform, an improved algorithm based on Hough one- dimensional transform is proposed. Firstly, the edges of images are detected and the disconnected edges are grouped. Then, the Hough one-dimensional transform is adopted to detect in line and group the edges so as to reduce computation complexity and space complexity. At last, the problems on over-connecting, endpoints determining and detection precision are solved by added accurately processing. The experimental results prove that the improved algorithm can effectively solve problems in the standard Hough transform, reduce missing detection and false detection, improve the detection accuracy and achieve detection in line for different content images.