The invention relates to a machine tool for machining a large gear in a spiral bevel gear pair and further relates to the machine tool of the large gear of the spiral bevel gear pair used for an automobile drive axle. Three sets of an X-axis guide rail, a Y-axis guide rail and a Z-axis guide rail which are vertical to each other are arranged on the top face of the machine tool body, and an X-axis slide table, a Y-axis slide table and a Z-axis slide table which move along corresponding guide rails under the action of a driving mechanism are arranged on the X-axis guide rail, the Y-axis guide rail and the Z-axis guide rail. A cutter plate or a grinding wheel is arranged at the bottom of the Z-axis slide table, and a shaft C capable of driving a machined workpiece to rotate is arranged in the Z-axis slide table. The machine tool further comprises a shaft B which penetrates through the front end face and the rear end face of the machine tool body. The front end of the shaft B is connected with a workpiece box, and the rear end of the shaft B is provided with a rotating mechanism driving the shaft to rotate B. A shaft A driving the machined workpiece to rotate is arranged in the workpiece box, and the shaft A is vertical to the shaft B. Compared with an existing device, the machine tool for machining the large gear in the spiral bevel gear pair has the advantages of being simple in structure, economic in cost, convenient to install and detach, capable of easily discharging chips and the like, and is particularly suitable for dry cutting and high-efficiency machining.