By the first-principle calculation method based on density functional theory, the adsorption processes of sulfur (S) doped, selenium (Se) doped and sulfur-selenium co-doped diamond substrates with different active groups were studied. The adsorption energy, Mulliken charge distribution and chemical bond overlap number of three different substrates with different hydrocarbon groups (C, CH, CH2, CH3) in the deposition atmosphere were calculated and analyzed. The results show that the covalent bonds between the sulfur doped model and C, CH and CH2 groups, the selenium doped model and C and CH groups, the sulfur and selenium co-doped model and C, CH and CH2 are formed through charge transferring. The bonds between sulfur doped model and CH group, and between sulfur and selenium co-doped model and C group are very close to the C—C bond of the ideal diamond. The addition of sulfur and selenium can add more growth active sites on the basis of the original diamond grain homoepitaxial growth.