The invention relates to an automatic control device and method for an exhaust fan of a high-voltage power distribution room. The method comprises the following steps: a temperature sensor monitors and sends real-time temperature to a common measurement and control system; the common measurement and control system compares the real-time temperature with a temperature starting lower limit value, and when the real-time temperature is higher than the temperature starting lower limit value, sends a temperature exceeding signal to a controller and simultaneously sends the real-time temperature to the controller; the controller sends a signal to start the exhaust fan for ventilation after receiving the temperature exceeding signal, and stops the exhaust fan when the real-time temperature reaches a temperature returning lower limit value. According to the method, the exhaust fan is automatically started for cooling under the condition that the temperature is excessively high, and is automatically stopped when the temperature reaches a preset value, so that the temperature of the high-voltage power distribution room can be reasonably controlled.