The invention discloses an automatic loading/unloading machine tool. The automatic loading/unloading machine tool comprises a machine tool, an X-direction loading conveying mechanism, an X-direction limiting clamping mechanism, a Y-direction clamping mechanism and a lifting push-out unloading mechanism. The automatic loading/unloading machine tool, provided by the invention, has the advantages that with the adoption of settings of loading conveying and pushing unloading, no repeated carrying and adjustment by workers is needed, the labor intensity of the workers is reduced, and the production efficiency and the machining precision of long square pipe workpieces are improved. The invention further provides an application method of the machine tool; and the automatic loading/unloading and the machining of long square pipe workpieces are finished through the arrangement of a lifting table in a matched manner, so that the operation is simple, the machining precision is high, and the production efficiency is high.