Polycrystalline diamond down-the-hole drill bit

The invention discloses a polycrystalline diamond down-the-hole drill bit which comprises a base, a base body is arranged in the center of the top end of the base, a shell is arranged at the top end of the outer wall of the base body, a substrate is arranged at the top end of the shell, grooves which are symmetrical front and back are formed in the center of the top end of the substrate, through holes are formed in the inner sides of the bottom ends of the two grooves, the bottom ends of inner cavities of the through holes communicate with the top end of an inner cavity of a diffusion groove,and a plurality of inner spraying holes are formed in the outer side of the bottom end of the diffusion groove in the circumferential direction. According to the polycrystalline diamond down-the-holedrill bit with a novel structure, the axial impact resistance of the polycrystalline diamond compact can be fully exerted, compared with the prior art, the shearing force borne by the polycrystallinediamond compact is reduced,