Abstract： A local light authentication mechanism based on security associations (LLAMSA) for network mobility (NEMO) in Proxy Mobile IPv6 Network was proposed. Based on the architecture of authentication, and authorization and accounting (AAA), the mechanism of optimized routing policy and extended security association was used to integrate authentication and address registration process, making the handover and authentication process to be limited in the local PMIPv6 domain. The performance analysis shows that LLAMSA not only implements the mutual authentication but also resists tamper attacks to protect the address registration information, improving the safety of NEMO. The performance of computation cost and authentication delay is better than existing mechanisms.