Abstract: In this paper thermodynamics analog calculation has been made for tube bloom in order to obtain a deoxidization technology and refining slag system. Industrial tests showed that if optical basicity and CaO /Al₂O₃ could be controlled at 0.75~0.80 and 2.0~2.5 respectively,then T[O]＜ 20 × 10^-6 in molten steel.T[O] decreases with increasing [Als] for bloom,where [Als] exceeds 0.015% then T[O] ＜ 20 × 10^-6,and[Als]＞0.020% then T[O]＜15 ×10^-6. The resulting technology can be effectively used to control the degree of purity. When T[O]≤2.0 × 10^-6,total content of non-metallic inclusion averages 21.6 ×10^-6 and all of the inclusion rating meet the requirements. For typical steel grades like B （PSL2） and JS25 Mn with stricter demand for [S]%,the average [S]have been controlled at 0.005% and 0.008% respectively.