The invention discloses a steel bridge recoating device. The device comprises a magnetic suction system, a cleaning system and a paint spraying system; the magnetic suction system is arranged on the bottom of the device and is used for attracting the device to the surface of a bridge bottom steel plate; the cleaning system and the paint spraying system are arranged on the upper portion of the device and used for cleaning the bridge bottom steel plate and the paint spraying work after cleaning respectively. The steel bridge recoating device can be hanged and walk on the surface of the bridge bottom steel plate, so that the rust removal and paint spraying work is conducted, rust stains and waste paint are recycled, and the problem that the manual operation is high in difficulty and dangerous is solved.