An exemplary wet processing apparatus includes a conveyor, a spraying system, and a suction system. The conveyor is configured for conveying a substrate. The spraying system includes an upper spraying conduit above the conveyor and an upper spraying nozzle mounted on the upper spraying conduit. The suction system includes a suction conduit and a suction nozzle connected to the suction conduit. The suction nozzle is adjacent to the conveyor and configured for suction the wet processing liquid sprayed on the substrate. The suction conduit is connected to the spraying conduit in such a manner that the flowing of the wet processing liquid in the upper spraying conduit can create a negative pressure in the suction conduit to enable the suction nozzle to suck the wet processing liquid on the substrate.