Abstract: Now, most of the tripartite authenticated key agreement protocols have been proven to be insecure.We design the new identity-based tripartite authenticated key agreement protocol, it is based on the secure IBE scheme by Peng.This protocol's security based on bilinear decisional Diffie-Hellman assumption.This protocol could provide known key security, PKG forward secrecy, key-compromise impersonation resilience and unknown key-share resilience, so it's a secure tripartite authenticated key agreement protocol.