For further reduction of oxygen, nitrogen and sulphur contents in master alloy GH3625, two vacuum induction remelting experiments (high vacuum without calcium and high vacuum with addition calcium) were carried out. Alloy composition and purity were investigated. The results show that: under high vacuum induction remelting burning loss and enrichment of alloying elements are all in the range of standard composition; deoxidation is excellent under high vacuum induction remelting, O content is reduced from 17ppm to 10ppm by C-O reaction; but removal of nitrogen and sulphur is not obvious; High vacuum induction remelting with addition Ca using Al2O3 Ca-O and Ca-Al2O3 (the inner wall of crucible) reaction is helpful to deep deoxidation, Ca-S reaction makes S content is greatly reduced, reducing nitrogen content is limited, it is far higher than N solubility in alloy GH3625. In Al2O3 crucible, adopting high vacuum melting technology and proper calcium addition amounts, oxygen, nitrogen and sulphur content could be reduced to 6ppm,60ppm and 9ppm respectively.