By the theory of syntonic mode-selecting in the compound ring in which a narrow-band taped fiber filter is embedded and by the uncoupling effect on the bidirectionally operating syntonic mode in the ring of the self-provided saturable absorption under the near threshold operation, a bidirectional, simultaneous, single-mode operating compact Er-doped fiber ring laser with the same frequency is realized, the measurement of rotation sensing of the all fiber ring laser is performed.