Foundation pit water pumping and filtering device

The invention relates to a foundation pit water pumping and filtering device which comprises a base, a cylindrical block is arranged above the base, a blind hole is formed in the lower end of the cylindrical block, a vertical pipe is arranged in the blind hole, a first filter cylinder is fixed to the lower end of the vertical pipe, and the lower end of the first filter cylinder is fixed to the base. The lower end of the vertical pipe is coaxially sleeved with a second filter cartridge, the second filter cartridge can slide up and down, the outer edge face of the cylindrical block is sleeved with an annular block, the annular block is a buoyancy block, the annular block vertically moves downwards to drive the second filter cartridge to move up and down in a reciprocating mode, and a drainage channel is jointly formed by the interval between the annular block and the base, the interval between the cylindrical block and the base and the vertical pipe; the annular block with buoyancy moves up and down on the wate