Abstract: Mobile IPv6 provides mobility support for the IPv6 Internet.Route optimization eliminates the triangular routing problem existing between the mobile node and correspondent node in mobile IP.However，mobile IPv6 brings some security threats at the same time，a great part of the threats are about the authorization and authentication problem of binding update in route optimization.Some security threats still exist in the return routability protocol and CGA-based protocol，the CAM-DH protocol is improved，a new enhanced protocol is proposed，the security is improved，and the computation and message exchange performance is optimized.