The invention provides an escalator step chain modeling and fault simulation method based on SIMPACK. In this method, the simulation model of an escalator step chain is established by dynamic simulation software SIMPACK, and a vibration acceleration sensor is installed on the driven shaft of the model. Three kinds of faults which are chain pitch elongation, pin and sleeve wear, roller and gear wear are added. Off-line integration of a normal state, a chain pitch elongation state, a pin and sleeve wear state, a roller and gear wear state is performed separately in SIMPACK, the off-line integration result is opened in the dynamic simulation software SIMPACK post-processor, and the required acceleration data of driven shaft transverse vibration are output. The acceleration data of driven shaft transverse vibration in four states are analyzed, and the fault laws in different states are studied. This simulation method can quickly and accurately simulate the operation state of the escalatorstep chain under various fault conditions, thus saving a lot of manpower, material and financial resources, and having great significance to avoid the occurrence of escalator faults.