Aiming at the defect that most existing protocols can't realize the mutual authentication among server, electronic tag and reader, this paper proposes a protocol which can realize the tripartite authentication based on R-LWE (learning with errors over ring) cryptosystem. The protocol used ideal lattice to encrypt important private information, and the encryption was mixed with different random numbers at the same time, which not only ensured the security of private information, but also made the message fresh and uncertain. The security analysis, formal proof based on GNY logic and performance analysis of the designed protocol show that the protocol has good security requirements, rigorous reasoning and better performance than its comparison protocol.