A ship wake automatic identification algorithm based on improved Hough Transform is proposed in this paper. First, the algorithm detects the ship and replaces the pixels’ gray value of the detected ship with the gray mean value of the image. Second, the peaks are modified in the Hough transform filed through setting a threshold. Third, ship wake detection and identification are realized automatically with improved Hough transform. Finally, it confirms the beginning and the end of the ship wake with constraint conditions. The experiment of wake detection in the advanced synthetic aperture radar image showed that the algorithm can detect ship wake, identify the kind of ship wake automatically and derive the beginning and end of the wake, which is significant for marine monitoring and management.