ZigBee is an emerging standard for wireless sensor networks. In order to study the security of the ZigBee standard, this paper analyzes the ZigBee security architecture , security model, key management methods and security mechanisms,and gives the encryption algorithm code to identify.The ZigBee security services can be applied to the MAC layer, network layer and the application layer.There are two types of safe modes:residential mode and commercial mode.There are also three keys:master key, link key and network key. The security of ZigBee depends on the CCM* mode of the AES128.There are also several security scheme:the CTR mode ensures confidentiality,the CBCMAC mode ensures data integrity,and the CCM* mode ensures both of them.We can see that ZigBee is a more secure wireless sensor network standard than others.