Drill bit special for hollow screw and capable of measuring drilling depth

The utility model relates to a drill bit special for a hollow screw and capable of measuring the drilling depth. The cutter comprises a handle part and a cutting part coaxially fixed at the lower endof the handle part, a central channel for the kirschner wire to penetrate through is formed in the central axis of the handle part and the cutting part; scale marks extending along the axis directionare arranged on the outer side wall of the handle part; side channels extending in the axial direction are formed in the side wall of the handle part and the side wall of the cutting part. A depth measuring rod is arranged in the side channel; the lower end of the sounding rod is connected with the upper end of the arc-shaped elbow; the lower end of the side wall of the cutting part is provided with a lower end hole allowing the lower end of the arc-shaped elbow to extend out of the side channel, a spring is clamped between the upper end of the depth measuring rod and the upper end wall of theside channel, and the uppe