Based on the analysis of available diesel engine design methods and means both home and abroad, the traditional design modes are summarized and their limitation and disadvantages are given. Digital and cooperative design method for the marine diesel engine adopting Top-down design philosophy is studied and its features and key technical points are concluded. Finally, based on Top-down and cooperative design platform, a certain diesel engine was taken as an example to introduce the process and method of digital and cooperative design for marine diesel engine.