The invention discloses a transformer room ventilating device of a mobile power supply vehicle. The transformer room ventilating device comprises two groups of fans FM1 and FM2, more than one blind window and a transformer temperature control box. The blind windows are arranged on the left side and the right side of a transformer room, control power supplies of the blind windows include a first power supply and a second power supply, the first power supply are shared by the blind windows and the fans, and the blind windows can be opened in advance when the fans need to be started; the second power supply is provided by a double-pole miniature circuit breaker in a PT (potential transformer) cabinet, the blind windows can be opened and closed under the individual control of the second power supply, control circuits of the blind windows can be individually controlled at the moment, and natural ventilating effects can be realized under the condition that the fans are not used; the fans FM2 are arranged at the right blind windows which are close to the front of the head of the mobile power supply vehicle. The transformer room ventilating device of the mobile power supply vehicle has the advantages that the transformer room ventilating device is additionally provided with the corresponding group of fans and the blind windows of the transformer room, the two groups of fans and the blind windows can act under manual or automatic control of a control system, and accordingly an effect of regulating the temperature of the transformer room can be realized.