Abstract: Petri net is a perfect model to describe and analyze concurrent systems. However， in large or complex applications of the real world， it may run into the problem that the amount of nodes is too large. Colored Petri nets and several hierarchical Petri nets， such as place/transition refinement nets， object nets and open nets are introduced. Also， the methods of deduction of amount of nodes and introduction of hierarchy into models are analyzed and compared. Further， the relations of these models with each other in view of their structures are discussed.

Key words: Petri net, hierarchy, place refinement, transition refinement, object Petri net, colored Petri net, open net

摘要： Petri网是一个很好地描述与分析并行系统的模型。但在实际应用中，如果系统过大或较复杂时，会遇到结点数过多的问题。介绍了着色网和几种层次结构的Petri网，包括位置/转移精化网、对象网以及开放网等；分析和比较了这几种模型用以减少结点数和引入层次结构的方法，而且从结构上讨论了它们相互之间的关系。

关键词: Petri网, 层次结构, 位置精化网, 转移精化网, 对象网, 着色网, 开放网,