The invention belongs to the technical field of a transformer protection device, and particularly relates to a 220kV transformer dual-float gas relay simulation action detection device and method. The220kV transformer dual-float gas relay simulation action detection device and method comprises a detected gas relay; both ends of the detected gas relay are respectively connected with butt flanges and the detected gas relay is arranged on a device fixed platform; the butt flanges at both ends are respectively connected with an oil tank of an oil injection circulation system via conduits; and thedetected gas relay is respectively and correspondingly connected with four terminals on a gas relay protection loop detection system. According to the invention, the simulation action detection device capable of accurately detecting insulation resistances of a protection circuit under different working conditions of the 220kV transformer gas relay is established; test requirements for the 220kV transformer gas relay protection loop are met; the device is simple in structure, can effectively detect a problem of failure of a protection action of the gas relay, and is applicable to greatly popularize and apply in the power industry.