The invention relates to milling of a special workpiece and further relates to an aluminum material cooling shell machining method. The aluminum material cooling shell machining method is resistant to deformation. The aluminum material cooling shell machining method comprises the process that the side faces, an inner cavity and a cavity bottom of a cuboid aluminum material are roughly machined, and the side faces, the bottom face and cooling grooves of the cuboid aluminum material are roughly machined; aging treatment is performed; and finish machining is performed on the inner cavity, holes in the side walls and corresponding threads in the holes, finish machining is performed on the cooling grooves at the two ends, finish machining is performed on the cooling groove which is located in the middle and not subjected to finish machining, and finish machining is performed on the side walls. The aluminum material cooling shell machining method has the beneficial effect that due to rough machining, aging treatment and finish machining, deformation of the workpiece is eliminated.