The invention relates to an exhaust device for a gas relay of a transformer. The exhaust device comprises a front-end connection element, an exhaust pipe, an exhaust valve and a sealing support element, wherein the front-end connection element is arranged at a front end of the exhaust pipe and is provided with an interface which can be connected with an exhaust nozzle of the gas relay, the exhaust valve is arranged at a tail end of the exhaust pipe, and the sealing support element sleeves the exhaust pipe and passes through a side wall of the gas relay. The exhaust device is arranged on an existing gas relay of the transformer, exhaust operation is not needed to be frequently operated on the gas relay, so that a maintainer is unnecessary to climb for operation, and meanwhile, the misoperation of the gas relay caused by oil leakage since a sealing component of the exhaust nozzle of the gas relay is loosen can also be prevented.