The emissions from traditional fossil heavy-duty trucks have become a conspicuous issue worldwide. The electrical road system (ERS) can offer a viable solution for achieving zero CO₂ emissions and has high energy efficiency in long-distance road cargo transport. While many kinds of pantograph structures have been developed for the ERS, their corresponding pantograph-catenary dynamic characteristics under different road conditions have not been investigated. This work performs a numerical study on the dynamics of the pantograph-catenary interaction of an ERS considering different pantograph structures. First, a pantograph-catenary-truck-road model is proposed. The reduced catenary model and reduced-plate model transmission method are used to minimize model scale. Three different types of ERS pantograph structures are considered in the model. After validation, the pantograph-catenary dynamics under the influence of truck-road interactions with complex road roughness and different pantographs are studied and compared. The corresponding vibration transmission mechanism is further focused. The results show that the truck-road interaction has a significant effect on the pantograph-catenary interaction, but the pantograph with only one lower and upper arm can isolate the roll vibration motion transmission from the truck to the collector head, which has the best dynamic performance and is suggested for use in the ERS.