The invention relates to a bremsstrahlung reflection triode for generating strong pulse hard X rays. The problems that the gap potentials of two cathodes and anodes of an existing bremsstrahlung reflection triode are inconsistent, and a radiation field cannot be fully utilized are solved. The triode comprises a reflection triode cavity, an anode base, an anode, cathodes, transverse cover plates, aforward cover plate, an insulation plate fixing nut, an insulation plate transition piece and an insulation plate. The part, connected with the insulation plate, of the reflection triode cavity is acylinder, the part, away from the insulation plate, of the reflection triode cavity is transited into a closed cavity, and two parallel flat plates are arranged on the opposite surfaces of the closedcavity; the two cathodes are respectively arranged on the two flat plates of the closed cavity; the anode is positioned between the two cathodes; the anode is arranged on the anode base, the anode base is installed on a water line inner cylinder through the insulation plate transition piece, and the insulation plate transition piece is fixed through the insulation plate fixing nut. The transversecover plates are arranged on the two flat plates of the closed cavity respectively, and the forward cover plate is arranged at the axial tail end of the closed cavity.