Abstract: Deoxidization reaction of high grade pipe steel refining in LF was calculated and analyzed in thermodynamics. The reasonable deoxidizer dosage was obtained. The effects of oxides in slag and the slagging process on desulphurization were investigated by comparing the different factors in industrial experiments. A better slag system and indexes were recommended to increase the desulphurization efficiency. The results indicate that the first 20 min during the LF process is the most important period of desulphurization. The new method can shorten the melting time by nearly 8 min.