The authentication key agreement is a scheme that generates a session key for encrypted communication between two participants. In the authentication key agreement, to provide the mutual authentication and the robust session key agreement is one of the important security requirements to enhance the security performance of key agreement. Recently Zhou et al. had proposed the key agreement protocol using pseudo-identifiers, but we found that there were weaknesses in their protocol. We have demonstrated that Zhou et al.’s protocol is vulnerable to replay attack, fails to provide mutual authentication, no key control, re-registration with the original identifier and efficiency in the verification of wrong password. We improved their scheme and proposed an improved authentication key agreement protocol that provides robust mutual authentication and the secure session key agreement. We analyzed its security performance using BAN logic and AVISPA tools and compared computational cost, communication overhead and security properties with other related schemes.