Notched hexago socket cap head screw

The utility model relates to a slotted inner hexagonal screw top cap bolt for external fixed equipment components of measurement while drilling (MWD), which consists of a screw top cap, a screw body, a slotted inner hexagonal screw top cap, and a convex outer hexagonal T-shaped wrench. A slotted inner hexagonal screw is arranged in the circular screw top cap to form the slotted inner hexagonal screw top cap, the screw cap in the bolt adopts a common screw cap, and the convex outer hexagonal T-shaped wrench matched with the groove of the top cap is manufactured. The slotted inner hexagonal screw top cap bolt solves the problems that after a fixed bolt of a fitting outside an instrument is eroded, the components of the instrument can not be dismounted and changed, and the maintenance difficulty of the equipment is increased in the prior art. The slotted inner hexagonal screw top cap bolt can be widely applied to the operation of the external fixed equipment components of the measurement while drilling (MWD).