The utility model relates to a grinding device for grinding the pipe mouth of a steel pipe, characterized in that it comprises a metal rotating shaft and a plurality of grinding rods, wherein one end of each grinding rod can be removably connected to the circumferential surface of the middle part of the metal rotating shaft, and the grinding rods are arranged around the axial centerline of the metal rotating shaft, and the axial centerlines of the grinding rods are located on a virtual conical surface. The utility model has the advantages of being able to be used for grinding the inner and outer edges of the pipe mouth, low resource consumption, low manufacturing difficulty, low manufacturing cost, low use cost and low maintenance cost.