Abstract: Described in the essay are the production of the X80 steel pipe used as support of the leg of the offshore jack-up drilling platform，covering such main aspects as chemical composition design，hi-purity/homogenization melting-continuous casting process， pipe-rolling process， and heat treatment， etc.Relevant analysis and statistics concerning the mechanical properties of the said pipe are made，and then the results are compared with related data of similar foreign-made products.Furthermore，according to applicable specification，relevant test to the welding process is conducted for evaluation purpose.As a result，it is revealed that the X80 steel pipe possesses all property values equivalent to or even higher than those of similar foreign-made products，and also has its low-temperature toughness much higher than that of the foreign ones，and high weldability as well.