The present disclosure discloses a device, system, and method for treating an ethylene oxide waste gas. The system includes a first pressure swing adsorption tower, a first thermostatic assembly, a gas storage tank, a first branch pipe, and a second branch pipe. The first pressure swing adsorption tower comprises a first accommodating chamber which accommodates an adsorption material. A first vent port and a first exhaust port are in communication with the first accommodating chamber. The first pressure swing adsorption tower is partially disposed in the first thermostatic assembly. The gas storage tank comprises a gas inlet/outlet port. The first branch pipe and the second branch pipe are in communication with the first vent port. The first branch pipe couples the first vent port with the gas inlet/outlet port and the second branch pipe introduces an ethylene oxide waste gas into the first pressure swing adsorption tower.