The invention discloses a cutting machine for an outer wrapping shell. The cutting machine comprises a milling assembly, a lifting assembly and a clamping device. The milling assembly comprises a milling cutter, a conical chuck, a pressing sleeve, a first transmission shaft, a first coupler, a first motor, a base, a rack, a base plate and a first supporting part. A conical hole is formed in the end portion of the lower end of the first transmission shaft; the conical chuck is arranged in the conical hole; and the milling cutter is arranged in the conical chuck. The lifting assembly comprises a second motor and a gear driven by the motor, and the gear is engaged with the rack. The clamping device comprises a hydraulic hollow vertical chuck, a positioning pillar, a chuck cover body and a scrap iron box body. Extrusion force of the pressing sleeve can make the conical chuck clamp the milling cutter. The scrap iron box body can prevent scrap iron milled from an upper cover of the outer wrapping shell from being splashed around, and the scrap iron is sharp and has radioactivity, and damage of the scrap iron to a human body is avoided; and the milling process is safe and reliable, remote operation can be achieved, and the human body is protected.