The invention discloses a substation green air exhaust system with noise reduction and smoke alarming functions, which comprises an air duct with two ends opened passing through each room sequentially. The air duct is internally provided with a plurality of air exhaust units; each air exhaust unit comprises a first transformer plate, a second transformer plate and a third transformer plate; the first transformer plate is arranged at one side inside the air duct; the second transformer plate and the third transformer plate are arranged at the other side inside the air duct; the second transformer plate, the air duct and a separator together form a second cavity with the left end opened; a third transformer plate, the air duct and the separator together form a third cavity with the right end opened; and positions, corresponding to the second cavity and the third cavity, on the air duct are respectively provided with a second air outlet and a third air outlet. The system of the invention makes full use of wind energy existing in the nature, air exhaust in the substation is completed on the premise of not consuming energy, not generating pollutants and not generating noise, and the system is energy-saving and green.