The operation of craniotomy to open the skull is roughly as follows: first, use an electric drill to select 4-5 holes on the surface of the skull to be removed, and drill holes with the skull; then use a nerve stripper to peel off the dura mater that adheres to the bone holes, and use a milling knife to mill each bone hole in turn; then form a bone window, or use a wire saw to saw between each bone hole; use a bone stripper to peel off the bone flap from the dura mater, and cut the dura mater in the next step, so that the intracranial lesions in the dura mater can be treated accordingly.