The invention discloses a dual-purpose automobile tail gas purifying device. A rotating shaft is fixed to an inner cavity of an automobile exhaust pipe. The outer wall of the rotating shaft is sleeved with an impeller set through a bearing, and a wind shield is inserted below the impeller set through a shaft rod; a tail gas purifier is arranged on the outer wall of the automobile exhaust pipe, and a storage battery is fixed to the top of the tail gas purifier; one end of a miniature telescopic motor is connected with a telescopic rod, and the other end of the telescopic rod is connected with the outer wall of the wind shield through the shaft rod; a filter screen is arranged in an inner cavity of the tail gas purifier which communicates with the inner cavity of the automobile exhaust pipe through the filter screen, a plasma purifier is arranged at the left side of the filter screen, an activated carbon filtering device is arranged at the left side of the plasma purifier, and an arc filtering plate is arranged at the left side of the activated carbon filtering device. The dual-purpose automobile tail gas purifying device is simple in structure and capable of effectively treating tail gas generated in the high-speed and idle speed process of an automobile.