The arrangement of machining production line of gearbox box body is the principle of first surface and then hole, and finally machining arachnids hole.In this arrangement, the porosity, sand holes, cracks and other defects of the casting blank can be exposed in the processing plane at first, so as to reduce unnecessary man-hour consumption. The machining process of the gearbox body basically divides into three stages, namely rough machining, semi-finishing and fine machining.The main processes include milling the datum plane of gearbox, milling the surface of conveying jaw, semi-finishing milling the front and rear end faces, finishing boring the bearing holes, and finishing milling the end faces of reversing axle holes.