These PKI is a kind of follow the standard use of public key encryption technology for the development of e-commerce to provide a secure foundation platform technology and specifications. The application of digital certificates is under the network environment to solve the problem such as identity authentication, access control, and information protection. This thesis mainly studied the part of the problem, this paper introduced the basic knowledge of cryptography and PKI theory foundation and basic system, of several common PKI trust model had carried on the detailed introduction, designed the distributed network environment, interconnection security platform of authentication and information encryption module.