The invention discloses an underwater propeller cleaning robot. A shifting assembly is arranged on the left side of an underwater robot assembly, and a mechanical claw assembly is arranged at the bottom of the underwater robot assembly; the underwater robot assembly comprises a first framework, an electronic cabin, a thruster and a power cabin, wherein the electronic cabin, the thruster and the power cabin are arranged in the first framework; the shifting assembly comprises a ceramic guide rail, the ceramic guide rail is arranged on the left side of the first framework and is provided with a self-locking motor, and linear modules and a corresponding second motor are arranged on the ceramic guide rail; the two linear modules are each provided with a manipulator, and a cleaning assembly is connected to each manipulator through a clamping hand; a bottom plate of the mechanical claw assembly is connected with the bottom of the first framework, two pairs of claws are arranged below the bottom plate, each pair of claws is provided with a second rotating shaft, the two second rotating shafts are connected through a coupler, the claws are connected with the bottom plate through first electric cylinders and are opened and retracted, each claw is connected with a finger through a second electric cylinder, and the fingers and the second electric cylinders realize opening and retracting.