Abstract: The appearance of high-speed railway makes wheel-rail transportation technology reaches a higher level. The increase of train speed puts forward higher requirement of traction power and dynamics performance. Moreover, the coupling effects between train and track, high-speed flow and other operation environments are intensified, which directly affect the operation quality and safety. In the initial development stage of high-speed train, the research focuses on how to ensure the high-speed, smooth and safe operation of the high-speed train. With the continuous increasing of running speed, the coupling effects between different subsystems of high-speed train become intense and can't be ignored. The service simulation of the train is more and more important. Today, the service simulation, health management and fault prognosis and early warning of high-speed train become the research hotspot. To master the global dynamic behavior of the system and to understand the micro-local vibration is the research direction of the system dynamics. Based on the requirement of high-speed train service simulation, this paper presents a modeling and calculation approach for long train formation based on the cyclic variable method, which can realize the simulation of any train formation and obtain the service status of vehicles in different train formation positions. A method of modeling the track and calculating the vehicle-track coupling interaction based on the sliding window method is proposed to obtain the service state of trains running on any long-term line. A method of long-term service calculation based on time-varying parameters is also proposed to perform the service simulation of trains in different service states and service time. Hence, the service simulation of train can be realized in different life-cycle based on the simulation frame proposed in the paper. Besides, this method can also be applied in simulations of the high-speed maglev train and even the high-speed evacuated tube train in the future.