The invention discloses a gas supercharging device for carbon dioxide flooding. The device comprises a tank body, a drainage pipe, a gas outlet pipe, an adjusting valve, a booster pump, a gas inlet pipe, a first barrel body, a motor, a spiral shaft, a flow guide pipe, a second barrel body, a top plate, a hydraulic cylinder, supporting legs, a pressing plate, a connecting rod, a limiting rod, a piston, a sealing ring, a supporting plate, a bearing seat, a rotating shaft, a roller, a washer, a fixed pipe, a connecting pipe, a sleeve, a conveying pipe, a gasket, a convex plate, a bolt, a box body, a box cover, a water outlet pipe, a water inlet pipe, a water pump, a circulating pipe, a separator plate and a diversion port. The device has the beneficial effects that the tank body is adopted for storing carbon dioxide, carbon dioxide gas can be compressed while carbon dioxide is conveyed, the pressurization effect of carbon dioxide is improved, the effect of mixing the carbon dioxide with crude oil is improved by adopting multi-stage gas compression, heat dissipation of the surface of the barrel body can be implemented, temperature adjustment is achieved, and adjustment on pressure and temperature in the carbon dioxide gas conveying process is facilitated.