Wireless sensor networks are composed of lots of sensor nodes, which work together for acquiring, processing information and then transferring them to observers. Meanwhile, sensor networks are resource-limited. Such as, memory capability, computation ability, communication bandwidth and range. Those limitations cause that security problem more difficult in this kind of network.Communication security is a very important problem in sensor networks. Feasible and effective key management mechanism is the one of key precondition . So the establishment of a symmetric pair-wise key shared between sensors is the most important. Firstly, the dissertation introduces the basic concepts including features, applications, research focus, security threats and security requirements, as well as the current research of key management. Secondly, without the trust third party, promotes a cluster-based pair-wise key management. Every two clusters nodes can share a key. Every two nodes in a same cluster can also share a key. This scheme can greatly decrease the need of storage and the overhead of communication. Furthermore, the overhead of key rekeying is decreased too. Thirdly, based on transversal design, a key pre-distribution scheme is proposed. It can enhance the security and can be against node capture efficiently, moreover, it can improve the key-sharing connectivity of sensor nodes. Based on the preceding chapter, combining of the new research direction of pair-wise key management, a path-key establishment is promoted. The simulations results demonstrate that our scheme can make two nodes which couldn't established pair-wise key establish a pair-wise key efficiently and safely.