The invention discloses a gas pumping device and method of an electric transformer, and belongs to the field of running maintenance and overhaul devices of electric transformers. An existing gas relay gas pumping device of the electric transformer has the problems of complex steps and inaccurate results. According to the gas pumping device, a guide pipe A (2) is communicated with a gas guide-out hole (8), and the other end of the guide pipe A (2) is fixedly provided with a needle (9); a guide pipe B (4) is provided with a gas stopping switch (10), and the two ends of the guide pipe B (4) are fixedly communicated with a gas storage bag (5) and a rubber sealing device (3) respectively. By means of the gas pumping method, the needle (9) installed on the guide pipe A (2) is inserted in the rubber sealing device (3), and gas pumping operation is conducted. The gas pumping device and method are easy and rapid to operate and reliable in detection result.