Abstract: Analyzed in the paper are the major control points for the development of ultra-high strength sulfur-resistant OCTG.The development and the production of BG125SS ultra-high strength sulfur-resistant OCTG are introduced and its applicability is studied.When producing BG125SS ultra-high strength sulfur-resistant OCTG, the content of Cr is lowered and that of V increased on the basis of Cr-Mo steel chemical composition, and the billet segregation is improved by slight reducing and electromagnetic stirring as well as by making a round billet from a big cross section casting blank.Furthermore, the rolling temperature is reasonably selected and a heat treatment process involving fast cooling+segmented air cooling is adopted.The properties of the final product can reach that of the SM125ES from Sumitomo Group.