A gas relay in the transformer, an important non-electricity protection equipment, only triggers the stem leaf spring for the serious gas alarm when the baffle rotates to a certain angle, which cannot judge the transformer fault in the event of heavy gas before running state and fault development process, this paper puts forward a kind of based on gas relay panel corner of transformer running state monitoring methods. The partial structure of the gas relay is improved, and the baffle corner signal is extracted by installing a Hall sensor on the back of the baffle. On this basis, this paper develops a test stand capable of simulating the baffle characteristics of gas relays at different fault energies. Subsequently, the baffle angle variation law under different fault energies is studied, and the influence of pipe pressure and pipe flow rate on the baffle angle is given. The results show that, based on this improved gas relay, the real-time baffle angle information can reflect the internal operating state of the transformer and provide an effective method for transformer operating condition monitoring.