Abstract: The research about secure protocol of IPv6 discusses the IPv6's secure protocol in aspects of IPSec's secure systems, the working principles, the working patterns, the methods of solving the secure problem and the application of it in VPN. IPSec's AH and ESP protocols provide authentication and encoding for IP layer's transmission. This character can solve the problem that today's secure system which can not protect the data in the IP layer but can protect the data in the application layer.