The invention discloses a sludge dewatering device comprising a sludge-water separation tank; an interstitial water removing assembly is fixed in the sludge-water separation tank, a water collecting tank is arranged below the sludge-water separation tank, and the interstitial water removing assembly communicates with the water collecting tank. The exterior of the sludge-water separation tank is ofa skeleton structure, the interior of the skeleton structure comprises filter cloth and a filter cloth protective layer from inside to outside, and the filter cloth and the filter cloth protective layer are attached and fixed. The interstitial water removing assembly comprises filter cores, filter cloth and interlayers, the filter cores are evenly distributed between the two interlayers, and thefilter cloth wraps the interlayers. The sludge dewatering device can be freely assembled according to the riverway coastal topography, the problem of land shortage of a sludge storage yard in urban riverway dredging engineering is solved, the water content of sludge treated by the device can be reduced to 80% or below, and the sludge is basically in a solid state and is convenient to transport. Inaddition, a power source is not needed in the dewatering process, and the sludge dewatering cost is reduced.