The growth and deposition process of chemical vapor deposition boron-doped and nitrogen-doped diamond were explored by the first-principles plane wave pseudo-potential method based on density functional theory. The diamond substrate model with hydrogen termination surface and single nitrogen-substituted or single boron-substituted were established, and the optimal stable structure of these models was calculated. The adsorption process and the adsorption difficulty of different hydrocarbon groups (C, CH, CH2, and CH3), boron-hydrogen groups (B, BH, and BH2) and nitrogen-hydrogen groups (N, NH, NH2) on different substrates with active site were studied. The results show that boron atoms and nitrogen atoms can be doped into the diamond lattice by in-situ substitution, and the two-hydrogen-bearing groups (BH2, NH2) are the most favorable doping groups. The nitrogen atom is difficult to form a nitrogen dimer after substitution into the diamond crystal lattice, which cannot be heavily doped, but the boron atom is more likely to form a boron dimer, so its heavy doping can be achieved.