In this paper, the authors had put forward a method to strengthen cooling of electrical transformer, which is using a draft funnel to induce self-generating air flow. The funnel is composed of a radiators or transformer surrounding enclosure, a duct and a transition which is used to connect the surrounding enclosure and the duct. The difference between the temperature of the air outside and inside the funnel causes a buoyancy force in the funnel, which can drive the air flow upward. As a result, the heat dissipation of the radiators will increase largely. This method can reduce the fan capacity or the number of operational fans, thereby reducing operation and maintenance costs. A case analysis shows that this method can meet the heat dissipation of panel radiators even without a fan.