The complex drilling conditions of deep drilling put forward higher requirements for the performance of impregnated diamond bits. To improve the application range of electroplated diamond bits， the effects of MnCl₂ and butynediol ethoxylate （BEO） on the surface morphology， microhardness， and thermal stability of the nickel base coating were studied. The drilling performance of pure Ni matrix diamond bit， Ni-Mn matrix diamond bit， and Ni-Mn matrix diamond bit with BEO as an additive after annealing at 300℃ for 1 hr was compared. The results show that the microhardness of pure Ni decreases significantly to 300HV after annealing at 300 ℃ for 1 hr， and the wear resistance of the annealed diamond bit with this matrix is too low， which leads to premature diamond shedding and a short service life to 2.94m. Both Ni-Mn coating and Ni-Mn coating with BEO added have good thermal stability， and the hardness increases to 640HV and 693HV respectively after annealing at 300℃ for 1hr. Ni-Mn matrix diamond bit has both suitable drilling life and drilling efficiency after annealing， and the bit life can reach 4.67m. However， the annealed Ni-Mn matrix diamond bit with BEO as an additive fails due to the matrix’s high microhardness.