Diamond drill bit

The invention discloses a diamond drill bit which comprises a drill bit base body. A cooling hole penetrating through the whole base body is formed in the center of the drill bit base body; a diamond abrasive disc is fixedly connected with the end portion of the drill bit base body and is of a round piece type structure; and notches in axial symmetry are formed in the periphery of the diamond abrasive disc and communicate with the cooling hole to serve as cooling liquid channels. The diamond abrasive disc provided with the notches in axial symmetry in the periphery is fixedly connected to an existing drill bit base body, so that the notches communicate with the cooling hole, intermediate cooling liquid can be guided from the cooling hole in the center of the drill bit base body and sprayed out of the notches of the diamond abrasive disc, and the flat bottom drilling function is achieved under the conditions of ensuring intermediate cooling and barrier-free chip removal. The diamond drill bit is simple in stru