The invention discloses a microwave plasma processing device, comprising a microwave source, a microwave circulator, a power regulator, a rectangular waveguide, a tuner, an antenna, a reaction box, a gas mixing system, and a vacuum system. The microwave source is connected to the microwave circulator, and the microwave The exit end of the circulator is connected to the rectangular waveguide, and the power conditioner is connected to the exit end of the microwave circulator and the microwave source respectively. The power conditioner adjusts the excitation power of the microwave source according to the microwave output power. A tuner is set on the side wall of the rectangular waveguide, and the reaction box is installed in the rectangular waveguide. On the side of the end of the waveguide, the antenna is inserted into the rectangular waveguide and the top of the reaction box, the gas mixing system injects the working medium gas into the reaction box, and the vacuum system evacuates the reaction box and maintains a vacuum state; the plasma cloud in the reaction box is subjected to electromagnetic force. Inner loop.