This paper proposes the Systematic Design Methodology of the Korean High Speed Train. High Speed Train does not operate in isolation and is a part of a rail system which is influenced through input and output effects from the environment and from the neighbouring system. To fullfil its overall desired function, such input and output relationships between the systems must be considered in the system boundary conditions. Therefore, the overall interrelationship of all these effects has to be carefully considered during the design process. Here proposed methodology may provide a guide line and criteria for the systematic problem solving method of that highly complex High Speed Train System.