The invention discloses a double-polarizer-based high-power millimeter-wave arbitrary polarization system comprising a first polarizer, a first commutating elbow, a corrugated waveguide intermediate transmission pipeline, a second polarizer and a second commutating elbow. The first polarizer is arranged at the first commutating elbow; the second polarizer is arranged at the second commutating elbow; the first commutating elbow and the second commutating elbow are connected by the corrugated waveguide intermediate transmission pipeline; and the centers of the first polarizer and the second polarizer are located at the axis of the corrugated waveguide. The first polarizer is used for changing a first rotation angle and thus changing a rotation angle and ellipticity of a high-power millimeterwave in the corrugated waveguide; and the second polarizer is used for changing a second rotation angle and thus changing a rotation angle and ellipticity of the high-power millimeter wave in the corrugated waveguide. On the basis of combination of the first polarizer and the second polarizer, arbitrary polarization of the high-power millimeter wave is realized. The double-polarizer-based high-power millimeter-wave arbitrary polarization system has advantages of simple design, low development difficulty and high maintainability.