The invention relates to a plate painting device. The plate painting device comprises a frame. A containing mechanism is arranged on the frame, a sliding rail is arranged above the containing mechanism, a fixed limiting plate is fixedly connected to the sliding rail, and a sliding limiting plate is slidably connected to the sliding rail; and a spring is connected between the sliding limiting plateand the frame. A rotating mechanism is arranged above the containing mechanism. The rotating mechanism comprises a rotating disc and a rotating ring. The rotating ring is rotationally connected to the rotating disc. A driving rod is fixedly connected to the rotating ring. A spraying head is arranged on the driving rod. A driven rod is connected to the rotating disc. A tension spring is connectedbetween the driven rod and the driving rod. A bracket is fixedly connected to the rotating disc. A rolling wheel is rotationally connected to the bracket. A fixing plate is rotationally connected to the bracket. Front limiting columns which abut against the driving rod and rear limiting columns which abut against the driven rod are arranged on the fixing plate. A driving mechanism is arranged on the frame. A driving roll attached to the rolling wheel in a friction manner is connected to the driving mechanism. A push mechanism is arranged on the containing mechanism. By the adoption of the scheme, plates in irregular shapes can be painted.