A two-way access authentication method comprises: According to the system parameters pre-established by the third entity, the first entity sends the access authentication request packet to the second entity, then the second entity validates whether the signature of first entity is correct, and if yes, the share master key of second entity is calculated; the second entity generates the access authentication response packet and sends it to the first entity, then the first entity validates whether the signature of access authentication response packet and the message integrity check code are correct; if yes, the share master key of first entity is calculated; the first entity sends the access authentication acknowledge packet to the second entity, then the second entity validates the integrity of the access authentication acknowledge packet, if passing the validation, the share master key of first entity is consistent with that of the second entity, and the access authentication is achieved. For improving the security, after received the access authentication request packet sent by the first entity, the second entity may perform the identity validity validation and generates the access authentication response packet after passing the validation.