Testing device and testing method of performance of fuel tank cap in dust environment

The present invention discloses a testing device and testing method of performance of a fuel tank cap in a dust environment. The testing device comprises a tank body, an air agitation device installed at one side of the tank body and an air pressure regulation device installed at the other side of the tank body. The cap at the top of the tank body is provided with a vent; the air pressure regulation device includes a piston barrel embedded in the tank body, a piston in the piston barrel and an actuator connected with the piston, and the inner wall of the piston barrel is connected with the fuel tank cap through the front end of an oil filling pipe; the side wall of the front end of the oil filling pipe is provided with a baroceptor which is connected with a control system, and the control system is configured to control the actuator; and there are provided dusts in the tank body. The fuel tank cap is disposed in a dust tank to perform detection, therefore the sealing performance, the breathing performance and the dust prevention performance of the fuel tank cap may be simultaneously detected.