An infrared sensor, comprising: a first electrode; a silicon substrate being provided on an upper surface of the first electrode; an isolation layer being provided on an upper surface of the silicon substrate; a second electrode being provided on an upper surface of the isolation layer; wherein the isolation layer is provided with a first window and a first inner side surface surrounding the first window, and the first window is used to expose a part of the upper surface of the silicon substrate; the second electrode is provided with a second window and a second inner side surface surrounding the second window, the second window fully exposing the first window; further comprising: a graphene film combined with the silicon substrate to form a Schottky junction; wherein the graphene film has a portion covering the part of the upper surface of the silicon substrate and forming the Schottky junction with the silicon substrate; the graphene film further covering the first inner side surface of the isolation layer, the second inner side surface of the second electrode and a part of the upper surface of the second electrode so that all sides of the graphene film are on the upper surface of the second electrode and spaced apart from an outer side of the second electrode; characterized in that the portion of the graphene film has a periodic nanostructure for absorption of a specific infrared wavelength by the infrared sensor. a first electrode; a silicon substrate being provided on an upper surface of the first electrode; an isolation layer being provided on an upper surface of the silicon substrate; a second electrode being provided on an upper surface of the isolation layer; wherein the isolation layer is provided with a first window and a first inner side surface surrounding the first window, and the first window is used to expose a part of the upper surface of the silicon substrate; the second electrode is provided with a second window and a second inner side surface surrounding the second window, the second window fully exposing the first window; further comprising: a graphene film combined with the silicon substrate to form a Schottky junction; wherein the graphene film has a portion covering the part of the upper surface of the silicon substrate and forming the Schottky junction with the silicon substrate; the graphene film further covering the first inner side surface of the isolation layer, the second inner side surface of the second electrode and a part of the upper surface of the second electrode so that all sides of the graphene film are on the upper surface of the second electrode and spaced apart from an outer side of the second electrode; characterized in that the portion of the graphene film has a periodic nanostructure for absorption of a specific infrared wavelength by the infrared sensor. a graphene film combined with the silicon substrate to form a Schottky junction; wherein the graphene film has a portion covering the part of the upper surface of the silicon substrate and forming the Schottky junction with the silicon substrate; the graphene film further covering the first inner side surface of the isolation layer, the second inner side surface of the second electrode and a part of the upper surface of the second electrode so that all sides of the graphene film are on the upper surface of the second electrode and spaced apart from an outer side of the second electrode; characterized in that the portion of the graphene film has a periodic nanostructure for absorption of a specific infrared wavelength by the infrared sensor.