Abstract: To meet the demand for the higher collapse resistance of OCTG by the oil field end-users, Baoshan Iron & Steel Corp. Ltd. has been, since 2006, engaged in a project for R & D of the extra-high anti-col- lapse oil casing. With the R & D approach of texture design and structure control to producing extra-high anti- collapse oil casing, the company has developed relevant steel type with its own IPR with which a kind of extra- high anti-collapse oil casing with a collapse value 65% higher than correspondent API value and insensitivity to yield strength is turned out. Also described here in the essay are the texture characteristics and the segregation phase characteristics of the said casing.