The invention relates to a wall-attached wind nozzle device with an adjustable guide plate and a control method thereof. A guide plate of a traditional nozzle is a fixed structure to cause the problem of incapability of adjusting the airflow direction. The wall-attached wind nozzle device comprises a wall-attached wind nozzle; the adjustable guide plate is arranged in the nozzle; a side wall water-cooled wall is provided with a detecting module; a reductive atmosphere area near the side wall water-cooled wall is measured through the detecting module; and the nozzle is guided by the guide plate to convey air into the reductive atmosphere area. The adjustable guide plate and the detecting module are added on the traditional nozzle structure; and under the guide effect of the guide plate, the air can be ejected to the reductive atmosphere area determined through the detecting module, and is input to change the concentration of oxygen and the concentration of carbon monoxide in the area, so that the reductive atmosphere in the area is weakened, the high-temperature corrosion resistance of the surface of the water-cooled wall in the area is effectively improved, the equipment service life is effectively prolonged, and the use cost is reduced through prolonging the service and maintenance periods.