The invention discloses a craniotomy drill, comprising a host machine, a speed reducer and a locking base which are in threaded connection in turn; a drill transmission rod connected with the output shaft of the speed reducer is inserted in the locking base; the craniotomy drill is characterized in that the host machine comprises a handle (1) at the lower side and a containing part (2) at the upper side; containing part (2) is internally provided with a stator having a DC motor and a rotor (5); and the wall (4) of the containing part (2) is the outer housing of the DC motor stator. The craniotomy drill has simple structure, and the wall of the containing part is directly used as the outer housing of the motor stator, thereby reducing the volume and reducing the entire weight. The craniotomy drill can prevent the motor from being slid off and can have comparatively high safety performance. Simultaneously, the craniotomy drill has integrated design and comparatively excellent waterproofperformance because of waterproof material and technique.