IPsec是虚拟专用网的一个标准，它规定了二个策略组件：安全关联数据库（SAD）和安全策略数据库（SPD）。IPsec系统中，安全策略主要通过SPD得到反应，而SAD是SPD的具体实现。本文首先给出安全策略的数据结构定义，然后给出安全策略的具体表示形式，最后编制程序，分别以命令的 IPsec is a standard for virtual private networks that specifies two policy components: the Security Association Database (SAD) and the Security Policy Database (SPD). In the IPsec system, the security policy is mainly responded by the SPD, and the SAD is the concrete realization of the SPD. This paper first gives the definition of the data structure of the security policy, and then gives the concrete form of the security policy. Finally, it compiles the program,