The invention relates to an extruding device with unique roller wheels for a disc type filter, which consists of roller wheels (1), an oil cylinder (2), a spring (3) and a fixed support (7), wherein the roller wheels are connected in series in rows end to end; the number of the roller wheels connected in series is determined by the length of a filter disc (5); two rows of the roller wheel assemblies are arranged symmetrically on two sides of the filter disc, the upper parts of every two rows of the roller wheel assemblies are connected and fixed with each other through the oil cylinder, whilethe lower parts are connected with the spring; the spring is fixed on a shell of the filter through the fixed support; and the filter disc can be provided with a few lines of two rows of the roller wheel assemblies. The roller wheel is tapered and the included angle between the central line of the roller wheel and the central line of the section of the filter disc is a degree so as to ensure thatthe linear velocity of the roller wheels connected together in series from the top down on the filter disc is equal to the linear velocity of the filter disc at each position. When the filter is drawn by vacuum until the moisture of a filter cake cannot be reduced, one extrusion is applied to the filter cake by the mechanical external force from the roller wheels in the extruding device so that the moisture content of the filtered filter cake is further reduced.