Abstract: Adopting the casing pounding technique to separate poor stratum is a common method in the field of current non-open excavation with horizontal directional drilling technology in oil/gas pipeline construction. However, the thickness and the structure computation for the casing are still based on empirical data. Considering the water and wastewater engineering industry in push pipe method and the field of non-open excavation, the limited length calculation formula for casing pounding-in, the method to calculate the casing thickness, the computation of hoop stress, the computation and stability analysis of longitudinal stress for the casing are presented based on the analysis results of the frictions between soil and casing, the end resistance of casing and the bending stress the casing subjected. The field application in a project showed that the theoretical computation and the field data were fitted well. It is considered that the computation results can provide a theoretical fundamental for the development and application regard to the horizontal directional drilling technique.