Mobile IPv6 is a very important part in the mobile computing for global Internet. However, there are some security threats in the current mobile IPv6 such as threats against binding update, Route Optimization and Tunneling. Therefore, strong security mechanism is required to provide authentication as well as address verification with better handover latency and efficient performance. This paper studies the security threats in the current mobile IPv6; meanwhile, summarize and analyze the existing Security Mechanism, infrastructures in the current mobile IPv6 and give the overview of this area.