Abstract: To better improve the ability and skill of operating marine electronically controlled diesel engine for marine engineers, chosen 7RT-FLEX60C diesel engine as the study object, a kind of visualization simulation system is developed for its fuel common rail system. The working principle of fuel common rail system is analyzed and its mathematical model is established based on the continuity equation and motion equation of fluid mechanics, the mathematical model is simulated and analyzed by applying MATLAB/Simulink. Based on the mathematical model, the 2D visualization simulation system is developed by using high-level computer programming language visual C# which can provide man machine interactive function and main parameters are real-time refreshed based on the mathematical model. The results showed that the visualization simulation system can be used to train marine engineers effectively and systematically.