The utility model discloses a vacuum degree alarm switch. The vacuum degree alarm switch is characterized in that a sheet-shaped plug is connected with a locating rod, the locating rod is in axial connection with a shielding sheet, a static contact sheet and a gasket successively, the gasket is riveted with the locating rod, an upper cover is in plastic composite connection with the locating rod and the sheet-shaped plug, a movable contact sheet, a diaphragm, and a spring seat gasket are in axial connection successively, the movable contact sheet is riveted with the spring seat gasket, the outer edge of the shielding sheet is provided with a flange towards the direction of the movable contact sheet, the upper cover and a rand are in clamping connection through clamping jaws, the matching joint between the upper portion of the inner ring of the rand and the upper portion of the upper cover is provided with small raised portions which are distributed uniformly, the matching joint between the lower portion of the inner ring of the rand and a lower housing is provided with small raised portions which are distributed uniformly, the lower housing is riveted with the upper cover, a space formed by the lower housing and the upper cover is used to extrude and fix the outer edge of the diaphragm, one end of a spring is connected with the spring seat gasket, the other end of the spring is connected with an adjusting screw, the adjusting screw and a fastening screw are axially serially connected and pressed against mutually, the adjusting screw and the fastening screw are in thread connection with the lower housing, a contact claw is in contact connection with the movable contact sheet, the upper cover is provided with an air inlet which is communicated vertically with a vent groove in the axial direction of the upper cover in the radial direction, and the end portion of the air inlet is provided with a small raised frustum.