The invention provides a tunable optical filter based on a dual-ring interferometer, belongs to the field of wavelength division multiplexing systems, and solves the problem that the conventional ring structure tunable optical filter is complex in structure, and only adopts a single waveguide material for realizing a communication network docking effect. The tunable optical filter comprises the dual-ring interferometer, a second phase modifier and a first coupler; after light enters the dual-ring interferometer, two paths of lights are formed and are outputted from the D end and the E end of the dual-ring interferometer respectively; light outputted from the D end is coupling induced transparency light, and light outputted from the E end is coupling induced absorption light; the second phase modifier is positioned between the D end of the dual-ring interferometer and the first coupler, and is used for adjusting phase difference between the coupling induced transparency light outputted from the D end and the coupling induced absorption light output from the E end, and then, the first coupler is used for performing interference on the received induced transparency light and the received coupling induced absorption light to form two bimodal paths of lights which are respectively outputted from the B end and the C end of the first coupler. The optical filter is mainly applied to a wavelength division multiplexing system.