A pulping cylinder of a pulping machine belongs to components of pulping machines and is used for solving the problems of high processing difficulty, low strength, poor crushing capacity and low filtering precision controllability of existing pulping cylinders and also the problems that the existing filter cylinder has no cutting edge and has no crushing function. The pulping cylinder comprises an upper pressure plate, a lower pressure plate and M circular pulping sheets. The M circular pulping sheets are stacked into a cylinder shape and fixed between the upper pressure plate and the lower pressure plate through guide bars. The upper surface of each circular pulping sheet which is annular is provided with radial, centripetal and evenly distributed grooves. A projection between each two grooves on the upper surface of each circular pulping sheet is provided with a sawtooth tip facing the center of the circular pulping sheet, lugs are evenly distributed on the outer periphery of the circular pulping sheet, and each lug is provided with a through hole. The pulping cylinder is standardized, so that filtering precision is guaranteed. The pulping cylinder is high in both rigidity and strength, so that material crushing effect is fine. The pulping cylinder is simple in processing, low in cost, convenient in mounting, and convenient in disassembly, cleaning and replacement, and the fact that the whole pulping cylinder is scrapped due to partial damage is avoided.