The invention provides a numerical-control machine tool for processing spiral bevel gear, which comprises a machine tool body, a workpiece box, a turn table of the workpiece box, a tool box and the supporting post of the tool box, wherein, the machine tool body is T-shaped, and two groups of rails X and Z which are perpendicular to each other are formed on the machine tool body; the turn table of the workpiece box is mounted on the rail X; the supporting post of the tool box is mounted on the rail Z; the workpiece box is mounted on the turn table thereof via turntable bearings; the supporting post of the tool box has a gantry structure, the sliding rail Y of the tool box is formed on one side of the gantry, and two traction screw rods are arranged in the gantry; and screw holes are formed on the tool box, the tool box is rotationally mounted on the traction screw rods via the screw holes, and one end of the tool box is stuck to the rail Y via slideway. The invention has the following advantages: the structure is reasonable, the operation and the application are convenient, the workpiece box has a small turning radius and large turning angle, the machine tool has small volume and stable operation, and the tool has high positioning accuracy, so that the invention is applicable to industrialized production, in particular to the numerical-control processing of large-size spiral bevel gear.