Facing the trend of energy crisis in the future, energy saving must start from aspects of the design. In China, the railway traction energy consumption is more than 80 per cent of energy consumption in the railway industry as a whole. First of all, this paper presents the energy consumption calculation of a single train, and analyzes the impact of energy consumption on the type of locomotive selection, then calculates total energy consumption and costs under the conditions of different ruling grades and route alternatives based on the life cycle of railway construction projects, which provides a scientific basis to determine the ruling grade and route alternatives. Finally, it illustrates an analysis of processes and methods of calculation through the Hainan West Ring Railway case.