The invention provides a method used for pressing and filtrating sludge. The method comprises the following steps sequentially: firstly, a plurality of parallel sludge filled-in spaces which can be compressed in an interlinking way are formed; secondly, the sludge to be filtrated is charged into the sludge filled-in spaces; thirdly, hydraulic pressure is adopted to compress the sludge filled-in spaces, so as to press and filtrate the sludge; fourthly, the sludge filled-in spaces are opened, and the sludge is discharged in a falling way. The invention also provides a sludge strong dewatering device which applies the method. The sludge strong dewatering device comprises a plurality of parallel plates which can move longitudinally and relatively along the arraying direction, one end of the dewatering device is provided with a hydraulic unit for driving the plates, each plate comprises a press plate with a concave surface and a press plate with a convex surface which are arranged adjacently; the dewatering device is provided with sealing parts between the press plate with the concave surface and the press plate with the convex plate when the two press plates have an insertion fit. Themethod can have high working efficiency, the dewatering pressure per square centimeter can reach 3 to 5 Mpa, the sludge water content can be reduced to be lower than 45 percent, and the sludge disposal amount is large, so as to be applicable to the processing need of the municipal sewage sludge.