Abstract: Described here in the paper are the main aspects of the HSM960 seamless steel tube serving as the boom of the extra-heavy-duty crane,including the technical characteristics,the manufacturing process and the quality.The said seamless steel tube is produced by means of adapting the design idea of strengthening the chemical composition with low carbon and multi-alloys,rolling with the MPM,and quenching and tempering heat treatment process,and possesses rather high strength,excellent plastic toughness and low-temperature impact resistance,and good weldability.The successful development of the said product has met the demand for the high strength and toughness steel tube by domestic engineering machinery circles.