The invention provides an authentication method and device of a roaming terminal, and a server. The authentication method of the roaming terminal includes the following steps that: negotiation with a terminal can be realized through a first TLS tunnel, such that the version of a PEAP in an authentication process can be determined; authentication information transmitted by the terminal is received by the first TLS tunnel; an attribution site server of the roaming terminal can be determined according to the authentication information; and the authentication information is forwarded to the attribution site server of the roaming terminal according to the version of the PEAP used by the roaming terminal, and PEAP authentication of the roaming terminal can be accomplished through the attribution site server. With the authentication method and device of the roaming terminal, and the server of the invention adopted, PEAP authenticated international roaming can be realized, and therefore, user intervention-free international roaming access can be provided for dominant intelligent terminals.