Noise reduction device and noise reduction method for preventing collision of rear door plate of compartment of dump truck

The noise reduction device comprises noise reduction mechanism main bodies, the noise reduction mechanism main bodies are used in pairs, are symmetrically installed at the corners of the lower portion of a carriage side door plate respectively, and are welded and fixed through a seat plate and the carriage side door plate; the noise reduction mechanism body is composed of a flange type oil cylinder, a piston, a piston rod, an ejector head, a buffering pad, a screw, a spring, a rubber pad, a throttling valve, an oil tank, an oil port cap, a seat plate, an oil cylinder installation seat, a rib plate and an impact seat. During unloading, the cushion on the outer end face of the top head collides with the impact seat, and impact force generated by swinging of the carriage rear door plate is absorbed and released by oil return resistance generated by the spring and the oil cylinder through the throttle valve, so that fastening noise generated when the carriage rear door plate collides with the end face of the carr