The invention discloses an automatic adjusting device for the reinforced concrete prefabricated panel perpendicularity and a using method thereof. The device comprises a movable ejector rod, a plumb assembly, a swing frame, a proximity switch, an installing base and a driving mechanism; the driving mechanism drives the movable ejector rod to move left and right; the plumb assembly and the swing frame are installed vertically and coaxially and can freely swing around an installing shaft inside the perpendicular plane, and the installing frame is supported on the movable ejector rod; the swing frame is provided with the proximity switch, when in the free state, the induction face and the tip end of a plumb are aligned, and the center of the induction face and the installing shaft are vertically aligned. The devices are used in pairs and are symmetrically installed on rigid fixing bases on the two sides of a prefabricated panel, when the wall panel perpendicularity does not meet the requirement, the induction face of one proximity switch in the two devices deviates from the tip end of the plumb, signals of the proximity switch change, and the adjusting device is controlled to move toadjust the inclination of the wall panel till the wall panel is perpendicular. The device is simple in structure, convenient to operate and capable of being automatically controlled, and is of quite positive significance in improving the fabricated building installing construction efficiency.