Abstract: In order to realize an optical filter with all-fiber structure and tunable center wavelength, a novel tunable optical filter made of the third-order high birefringence fiber loop mirror and electromagnetic force based cantilever tuning unit was proposed. The transmission process of the loop mirror and the principle of the cantilever tuning unit were analyzed. The pass-band can be tuned by controlling the input current of the cantilever tuning unit. Thus it turns out that the filter possesses the characteristics of good tunability, fine output spectrum, etc.As a result, it can be used for selectively output of light-wave at different wavelengths.