The invention discloses an atmospheric supersonic-speed plasma spraying device capable of forming a shielding gas hood. The atmospheric supersonic-speed plasma spraying device capable of forming the shielding gas hood comprises an anode nozzle, wherein the anode nozzle is in the shape of a rotating body and is provided with a central through hole. The anode nozzle is further provided with a shielding gas hole and a powder feeding hole, wherein the inlet end of the shielding gas hole is arranged on the circumferential surface of the anode nozzle, the outlet end of the shielding gas hole communicates with the central through hole, and an acute angle alpha is formed between the axis of the shielding gas hole and the axis of the central through hole; and the inlet end of the powder feeding hole is arranged on the circumferential surface of the anode nozzle, the outlet end of the power feeding hole communicates with the central through hole, and the axis of the powder feeding hole is perpendicular to the axis of the central through hole. The atmospheric supersonic-speed plasma spraying device capable of forming the shielding gas hood is simple in structure and is not provided with a solid hood, a cold water device does not need to be additionally arranged, and mounting, dismounting and checking are convenient; and sprayed materials are not prone to adhering to a duct of a nozzle, jet flow and the atmospheric environment are isolated to a certain extent by shielding gas, oxidation of sprayed particles in the jet flow can be reduced, the jet flow is cooled to a certain extent, the temperature of the jet flow and the temperature of the sprayed particles are decreased accordingly, and the probability of oxidation of the sprayed particles is lowered.