In this paper, a key management scheme in cryptosystem for hierarchy is proposed using symmetric cryptography technology, asymmetric cryptography technology, symmetric cryptography combined with asymmetric cryptography technology. At the same time, it's security and efficiency are analyzed. Comparing with the exist systems, this scheme adopts tree model, the users of different secure levels contact each other with relation parameters, the system is appropriate for not only the common environments, but also the special environments in which key changes frequently and users change dynamically.