The continuous movement of high-speed train results in the pantograph interacting with a long catenary structure. The traditional methods based on the Lagrangian description can only model the whole long catenary structure, which decreases their calculation efficiency. In this work, a reduced pantograph–catenary interaction model is developed to accurately and efficiently simulate the pantograph-catenary interaction with the long catenary structure. In the model, the long catenary is reduced to a small region around the moving pantograph, and the arbitrary Lagrangian‒Eulerian (ALE) method and modal superposition method (MSM) are used to model this small area. The pantograph is modeled as a multi-rigid body system. The pantograph and reduced catenary model formulate the reduced pantograph–catenary interaction model. Because the long catenary structure is reduced to a small moving region, the number of degrees of freedom (DOF) of the model is significantly decreased. The present model is validated by the EN 50318:2018 standard with a long catenary structure considered. The calculation results show that the present model is accurate and efficient in the investigation of long-term pantograph-catenary interaction dynamics.