The utility model belongs to the field of cutting equipment, and particularly relates to a portable composite insulator sheath cutting device. The device is composed of a fixing device, four spiral micrometer devices and a cutting unit. The fixing device is composed of two semicircular plates to be of a cylindrical structure. Four screw holes are evenly formed in one cross section of the fixing device. The four spiral micrometer devices are installed in the four screw holes in the fixing device respectively. The cutting unit is installed on the upper end face of the fixing device. The cutting unit is provided with blades capable of feeding. According to the portable composite insulator sheath cutting device, the method of determining the circle center through four points is adopted, and the spiral micrometer structure is adopted, so that it is ensured that the cutting device is coaxial with an object to be cut, and the minimum error can reach 0.1 mm; the blades of the spiral micrometer structure are adopted, so that the cutting thickness is controllable, and the cutting precision is ensured; undamaged cutting of composite insulation sheathes is achieved.