Abstract: Described here in the essay are the main aspects of the steel pipe semi-immersion quenching process,involving the work principle,and the structural features of the equipment.Owing to use of the quenching process of "external showering + internal spray + bathing + rotation" to get the steel pipe over-length quenched,not only the requirements for cooling capacities for pipes with different wall thicknesses are satisfied,and the martensite content is increased after the quenching,but also it is ensured that the whole length and full-cross section properties of the steel pipe are more homogeneous,and that the hardness difference is further reduced.Moreover since the lower part of the steel pipe fully contacts the cooling water in the bath,the compression ring belt soft points are eliminated,and meanwhile the straightness of the pipe is improved obviously.