The utility model discloses a flange gasket manufacturing tool which can be used for manufacturing various flange gaskets in accordance with requirements on flange parts, and is convenient and rapid. The flange gasket manufacturing tool comprises a central positioning part and a cutting part, wherein the central positioning part and the cutting part are mounted on a sliding rod. The flange gasket manufacturing tool is fixed in the center of a gasket sheet material, the sliding rod is rotated, the cutting part is enabled to rotate around the center of the positioning part, and the sheet material is cut into a gasket. The flange gasket manufacturing tool is convenient and practical in manufacturing the flange gasket, and a tool rest is adjustable. A flange gasket in any size can be manufactured on the premise that the sliding rod is long enough, the specific models of the flange parts are not needed to be known in advance, and onsite measurement and onsite manufacturing are carried out. The flange gasket manufacturing tool is particularly applicable to manufacturing non-standard flange gaskets and the occasions that a flange gasket cannot be rolled according to a ready-made flange, and a flange gasket cannot be rolled on a flange part. The flange gasket manufacturing tool is simple in structure, small and practical and can be carried about, so that the working efficiency on the maintenance of the flange parts is effectively improved, and the working intensity is reduced for workers.