The working principles and methods of wake images digital processing system were introduced. The gray-scale transformation, filtering, Canny marginalization, binary transformation and histogram transformation of two wake flow images were carried on, the speed of which are 30 km/h and 40 km/h respectively, using MATLAB software, experimental results were analyzed,and the speed of the ship wake edge angle, edge curvature and histogram peak change were obtained. The research results provide a basis for wave images entering the informationization system.