Abstract:Post information network is made up of two parts which integrated network and financial computer network of post. The design of security mechanism to postal information network is one of the key question in construction of postal information. It relates to great benefit of post enterprise, affects construction result of total system directly. This paper starts out from every systematic application and security needs, it analyses and studies about related technology of security network, raises a security mechanism of postal information network in view of technology for Kerberos and RBAC. The solving schemas pays a special attention to combine with postal information network closely, having higher reference value.