An anonymous authentication method based on a pre-shared key, a reader-writer, an electronic tag and an anonymous bidirectional authentication system are disclosed. The method comprises the following steps: 1) a reader-writer sends an accessing authentication requirement group to the electronic tag; 2) after the electronic tag receives the accessing authentication requirement group, an accessing authentication response group is constructed and sent to the reader-writer; 3) after the reader-writer receives the accessing authentication response group, an accessing authentication confirmation group is constructed and sent to the electronic tag; 4) the electronic tag carries out confirmation according to the accessing authentication confirmation group.