The invention discloses a PIT effect-based all-optical switch. The switch comprises a silicon dioxide substrate, a metal layer, a graphene layer, a first resonant cavity and a second resonant cavity;the silicon dioxide substrate is horizontally arranged; the metal layer is horizontally arranged at the upper end of the silicon dioxide substrate; a strip-shaped waveguide which extends in a front-back direction is arranged at the upper end of the metal layer; the two ends of the waveguide extend horizontally to the front end and the rear end of the metal layer respectively; the first resonant cavity and the second resonant cavity are arranged at the upper end of the metal layer at intervals in the front-back direction, and are positioned on the left side and the right side of the waveguide respectively; both the first resonant cavity and the second resonant cavity communicate with the waveguide; the graphene layer is arranged between the first resonant cavity and the second resonant cavity, and fills the waveguide; and the waveguide is filled with air. The PIT effect-based all-optical switch has the advantages of being small in size, low in power consumption and high in response speed.