Abstract: Three-party password-based authenticated key exchange protocols allow two clients to authenticate each other and establish a shared session key through a trusted server who preserves clients' passwords or verifiers about passwords. However, because of the low entropy of passwords, password-based authenticated key exchange protocols are vulnerable to dictionary attacks. Based on available protocols, a new efficient three-party password-based authenticated key exchange protocol is proposed by combining the symmetric encryption algorithm with the method of two-party key exchange protocol of Diffie-Hellman. Results indicate that and the proposed protocol can resist against various attacks and provide the perfect forward security.