As the core transmission component of the escalator, the main drive chain plays a critical role in the system’s overall operation. It transmits power from the motor to the escalator’s transmission components, ensuring the escalator operates continuously and smoothly. Prolonged use leads to wear between the pin and the bush, and causes chain elongation. This wear is particularly exacerbated under conditions of large variable load, which can adversely affect the performance of the escalator and pose a safety risk to passengers. Therefore, based on dynamics theory, this paper utilizes the multi-body dynamics simulation software RecurDyn to construct a simulation model of the main drive chain for detailed analysis. This study concentrates on a single link of the main drive chain, and analyzes the wear characteristics between the pin and the bush. It further investigates the damage evolution of the main drive chain under large variable load through the Archard wear model. Furthermore, the dynamic characteristics of the chain at various elongation levels are analyzed, establishing a relationship between the stabilized chain tension, the vibration stability of the main drive chain, and the chain elongation rate. This provides a fundamental basis for the condition monitoring and damage assessment of the main drive chain.