Oriented at the aim and existing problem, this paper starts from the strategy and complexity of internal urban rail transit, explaining the substitution of traditional engineering thinking and the effectiveness of using new system thinking to solve problems. The realization of the sustainable development of urban rail transit and the necessity of creating a new cross-discipline "Metro Science" were proposed for the first time. A comprehensive analysis using the "three factors" method was carried out on the feasibility of creating metro science. Finally, the knowledge system and creation path of metro science were put forward preliminary. The research methods of urban rail transit and metro science methodology are implemented through this paper consistently.