The denitrogenation and desulphurization behavior during vacuum induction melting (VIM) refining Ni base superalloy using CaO crucible was studied. It has been found that the desulphurization process did not occur by only using CaO crucible. Combining with the results of XRD and composition analysis, the desulphurization mechanism of CaO crucible was proposed. Al addition limits effect on denitrogenation, but it is very important for desulphurization. Ti addition has adverse effect on denitrogenation. The increase of vacuum is a powerful measurement to accelerate the denitrogenation process. The denitrogenation and desulphurization behavior during vacuum induction melting (VIM) refining Ni base superalloy using CaO crucible was studied. It has been found that the desulphurization process did not occur by only using CaO crucible. Combining with the results of XRD and composition analysis, the The addition of effect effect on denitrogenation, but it is very important for desulfurization. Ti addition has adverse effect on denitrogenation. The increase of vacuum is a powerful measurement to accelerate the denitrogenation process.