The invention discloses a sulfur hexafluoride/nitrogen mixed gas inflating device and method. The sulfur hexafluoride/nitrogen mixed gas inflating device comprises an SF6 gas inlet connector, a N2 gas inlet connector, a monitoring module, a flow control valve set, a vacuumizing module and a gas inflating outlet; the SF6 gas inlet connector, the N2 gas inlet connector, the monitoring module, the vacuumizing module and the gas inflating outlet are all communicated with the flow control valve set; the flow control valve set is a multi-way valve; the flow control valve set is provided with a valve S1, a valve S2, a valve S3, a valve S4 and a valve S5; and the valve S1 is arranged between a SF6 gas bottle and the SF6 gas inlet connector, the valve S2 is arranged between a N2 gas bottle and the N2 gas inlet connector, the valve S3 is arranged between the monitoring module and the multi-way valve, the valve S4 is arranged between the vacuumizing module and the multi-way valve, and the valve S5 is arranged between an air inflation outlet and a to-be-inflated device. According to the sulfur hexafluoride/nitrogen mixed gas inflating device and method, a current transformer is inflated through mixed gas inflating device, the accuracy requirement and the insulation requirement of on-site inflation to the mixed gas proportion and pressure are met, operation is convenient and quick, and cost is low.