The invention discloses a four-channel optical filter based on a PIT effect. The optical filter comprises a silicon dioxide substrate, a metal layer, a graphene layer, two first resonant cavities, a second resonant cavity, a third resonant cavity, a fourth resonant cavity and a fifth resonant cavity, the silicon dioxide substrate is horizontally arranged, and the metal layer is horizontally arranged at the upper end of the silicon dioxide substrate; a strip waveguide extending in the forward and backward directions is arranged at the upper end of the silicon dioxide substrate, the two ends ofthe waveguide respectively extend to the front and back ends of the metal layer horizontally, and the two first resonant cavities are respectively arranged at the upper end of the metal layer at an interval in the forward and backward directions and located on the left and right sides of the waveguide; the two first resonant cavities are communicated with the waveguide, the graphene layer is arranged between the two first resonant cavities, and the waveguide is filled with the graphene layer. The optical filter has the advantages that power consumption is low, and the size is small.