The invention relates to the technical field of fire protection equipment machining auxiliary devices, in particular to a fire protection pipeline outer wall grinding device. By means of the fire protection pipeline outer wall grinding device, the containing stability of a ground fire protection pipeline on a grinding table can be improved, and usage reliability is improved; and grinding through manual usage of an electric hand drill is not needed, manpower is relieved, the grinding effect is improved, a grinding wheel can well make contact with the outer wall of the fire protection pipeline,and usage limitation is reduced. The fire protection pipeline outer wall grinding device comprises a grinding table, two left support columns, two right support columns, a left fixing plate, a right fixing plate, two left limiting sliding blocks, two right limiting sliding blocks, a left baffle, a right baffle, a left adjusting lead screw, a right adjusting lead screw, a left upper sliding block,a left lower sliding block, a left upper supporting plate, a left lower supporting plate, a right upper sliding block, a right lower sliding block, a right upper supporting plate and a right lower supporting plate are included. A rear side plate, a left rotation shaft, a right rotation shaft, a gear motor and a fixing block are further included, and a drive gear is arranged at the output end of the left portion of the gear motor and engaged with a driven gear.