A liquid knife cleaning apparatus and a liquid knife are provided. The liquid knife cleaning apparatus includes: a frame configured to be arranged on the liquid knife and be capable of reciprocating in an extending direction of the knife edge; a cleaning blade configured to extend into the knife edge of the liquid knife and be capable of reciprocating inside the knife edge under the driving of the frame to clean the knife edge, the cleaning blade being arranged on the frame; and a movable mechanism configured to control the frame to reciprocate on the liquid knife in the extending direction of the knife edge, the frame being connected to the movable mechanism.