We studied the energetic behaviors of interstitial and substitution carbon(C)/nitrogen(N) impurities as well as their interactions with the vacancy in vanadium by first-principles simulations. Both C and N impurities prefer the octahedral site(O-site). N exhibits a lower formation energy than C. Due to the hybridization between vanadium-d and N/C-p, the N-p states are located at the energy from-6.00 e V to-5.00 e V, which is much deeper than that from-5.00 e V to-3.00 e V for the C-p states. Two impurities in bulk vanadium, C–C, C–N, and N–N can be paired up at the two neighboring Osites along the 111 direction and the binding energies of the pairs are 0.227 e V, 0.162 e V, and 0.201 e V, respectively.Further, we find that both C and N do not prefer to stay at the vacancy center and its vicinity, but occupy the O-site off the vacancy in the interstitial lattice in vanadium. The possible physical mechanism is that C/N in the O-site tends to form a carbide/nitride-like structure with its neighboring vanadium atoms, leading to the formation of the strong C/N–vanadium bonding containing a covalent component. We studied the energetic behaviors of interstitial and substitution carbon (C) / nitrogen (N) impurities as well as their interactions with the vacancy in vanadium by first-principles simulations. Both C and Nbly prefer to octahedral site (O-site). N exhibits a lower formation energy than C. Due to the hybridization between vanadium-d and N / Cp, the Np states are located at the energy from-6.00 eV to-5.00 eV, which is much deeper than that from-5.00 eV to-3.00 eV for the Cp states. Two impurities in bulk vanadium, C-C, C-N, and N-N can be paired up at the two neighboring Osites along the 111 direction and the binding energies of the pairs are 0.227 e V, 0.162 e V, and 0.201 e V, respectively. Future, we find that both C and N do not prefer to stay at the vacancy center and its vicinity, but occupy the O-site off the vacancy in the interstitial lattice in vanadium. The possible physical mechanism is that C / N in the O-site tends to form a carbide / nitride-like structure wi th its neighboring vanadium atoms, leading to the formation of the strong C / N-vanadium bonding containing a covalent component.