Folded corner plug door installed in the general air duct and train tube of rolling stock, to close or open the general air duct, train tube compressed air pathway, the product in the design of the use of anti-closing device, folded corner plug door only after the handle is lifted to open and close the operation, folded corner plug door according to its different installation position, can be divided into right-closing plug door and left-closing plug door, two kinds of plug door structure and installation method is the same, only Handle switch direction is different. Folded angle plug door in the valve body is equipped with exhaust holes, when the folded angle plug door is closed, can be quickly discharged from the folded angle plug door out of the end of the pipeline connected to the compressed air