The invention discloses an automatic ventilation energy-energy-saving outdoor machine room for a region with large day and night temperature difference changes, and relates to an outdoor machine room.In order to solve the problems that energy consumption of an existing outdoor machine room air conditioner is excessively large at the region with large day and night temperature difference changes,a vent hole is formed in a side plate, and a turnover plate is arranged at the vent hole; the turnover plate is in rigid connection with a rotating shaft through a shaft connecting body; a U-shaped fixing frame is fixed to the inner wall of the side plate; a dustproof rain cover is arranged at the outer wall of the side plate; the rotating shaft is in shaft connection with a fixing frame; a temperature sensing coiled spring is connected with the rotating shaft, and the temperature sensing coiled spring is fixed to the fixing frame; the temperature sensing coiled spring pulls the rotating shaftto rotate under low temperature, and then, the turnover plate is driven to increase the area of the portion shielding the vent hole till the turnover plate completely covers the vent hole. The temperature sensing coiled spring pulls the rotating shaft to rotate reversely under high temperature, and then, the turnover plate is driven to reduce the area of the portion shielding the vent hole till the ventilation amount of the vent hole is the maximum. The machine room has the advantages that the operation time of an air conditioner is shortened, the purpose of lowering energy consumption of theair conditioner is achieved, and the machine room is applicable to being installed on the region with large day and nigh temperature differences.