The utility model discloses a filter pressing sludge dewatering device, and belongs to the technical field of sludge dewatering devices. The dehydration device comprises an air compressor, a filter pressing chamber and a filtrate collector; the filter pressing chamber comprises a cover plate, a cavity barrel and a bottom cover; an air inlet valve and an exhaust valve are distributed on the cover plate; a piston is arranged in the cavity cylinder body; the edge of the piston is embedded into the sealing rubber ring; flow guide holes are distributed in the bottom cover; isolation filter cloth iscushioned on the flow guide holes; an isolation steel mesh is cushioned on the isolation filter cloth; and supporting columns are distributed below the bottom cover. By simulating the plate frame dehydration process, the reality that a large amount of sludge needs to be conditioned when the actual dehydration effect of the sludge is verified through plate frame dehydration is overcome, and the problem that the actual dehydration effect of the sludge cannot be verified due to the fact that the sludge volume is too small in the laboratory research stage is solved.