The invention discloses a machine tool for automatically chamfering inner and outer corners and flattening end surfaces of pipe fittings. The machine tool comprises a machine shell, a main shaft, a clamping mechanism and a cutterhead arranged on the main shaft, wherein the periphery of one side of the main shaft is connected with a main shaft sleeve through a bearing, and the other side of the main shaft is connected with a roller through a spline; the outer side of the roller is fixedly connected with a belt wheel; the roller is connected with the machine shell through a bearing; the machine shell is provided with a first guide rod parallel to the main shaft, and the first guide rod is provided with a first sliding block; the first sliding block is fixedly connected with the main shaft sleeve through a shifting rod; the shifting rod is connected with a first air cylinder; and an air cylinder rod of the first air cylinder is arranged parallel to the main shaft. By adopting the structure, the main shaft sleeve and the main shaft are driven to be telescopic through pushing with the first air cylinder, and the belt wheel for driving the main shaft does not move, so that feeding energy consumption is reduced; and meanwhile, the feeding size is small, collision is not prone to occurrence, and safety accidents are reduced.