The invention relates to a paint brushing device, in particular to an arc-shaped plate paint brushing device for a building. The arc-shaped plate paint brushing device for the building is uniform in paint brushing, high in paint brushing and easy to operate. The arc-shaped plate paint brushing device for the building comprises a left frame, a bottom plate, a sliding rail, a slider I, iron blocks, an electromagnet, a slider II, springs I, a rotary motor, a connection rod I, a paint box, an electric wheel I, a pull wire, a cover, an electric wheel II, a connection rod II, a supporting rod I, a spring II, a steel wire rope, a supporting rod II, an electric push rod, a brush and a thumb cylinder. The left frame is arranged at the left end of the bottom plate, the electric wheel I is arranged on the upper portion of the right side of the left frame, and the pull wire is wound on the electric wheel I. The effects of uniform paint brushing, high paint brushing speed and easy operation are achieved, by means of the device, an arc-shaped plate can be efficiently brushed with paint, and work efficiency is improved.