针对平面机构拓扑结构组成特点,提出平面机构动力学建模的复合方法.依据机构结构学原理划分动力学建模的单元,采用状态空间方法表达系统动力学模型.采用平面四杆机构作为建模案例,与现有多体系统建模方法对比,验证了新方法的正确性.新方法可以很好地支持动力学模型的重用,揭示了平面机构动力学模型与拓扑结构的内在联系. According to the topological structure of plane mechanism, a composite method of plane mechanism dynamics modeling is put forward. According to the mechanism of mechanism structure, the dynamic modeling unit is divided and the state space method is used to express the system dynamics model. Compared with the existing multi-body modeling method, the new method is proved to be correct, and the new method can well support the re-use of the dynamic model, revealing the intrinsic relationship between the dynamics model of the planar mechanism and the topological structure.