The invention relates to a device for automatic sand blasting and rust removal. Two support plates are in a horseshoe shape, and a tooth ring and an enhanced ring are respectively fixed on an inner side of a support plate. The inner side of each support plate is provided with external guide wheels distributed in a circular arc line on the upper part of the support plate, and internal guide wheels are uniformly distributed in a circular arc line at the lower part of the support plate. The tooth ring and the enhanced ring are concentric with the external guide wheels and the inner guide wheels, and are at the direction and positions as the openings of the support plates. Two arc plates, having radian matched with the arcs uniformly provided with the external guide wheels and the internal guide wheels, are connected into a whole. A motor is fixed on one side of an arc plate, and one end of a transmission shaft passes through the arc plates and is connected to a driving gear at the external side. Two arc plates are clamped into grooves of the external guide wheels and the inner guide wheels. A driving gear is engaged with the ring gear. Two swing spray gun components are symmetrically fixed on a swinging mounting assembly through swing bearing seats. The device can realize automatic rust removal in a fast, simple and stable way, reaches quality requirements for construction in an efficient and environment-friendly manner, and reduces the original operation time by half.