A method describing Take Grant system using the Petri net, which is called PTGS (Petri Taken Grant System) model, is introduced, and applied to the problem of leaking access rights using PTGS.

• 介绍了用Petri网描述获取授予系统的PTGS模型的方法 ；并利用PTGS模型探讨保护系统中访问权利泄漏或被窃取的问题 .