Abstract: In order to decrease the hydraulic pressure in the expandable tubular operation and enhance the HSE standard, the paper analyze the two kinds of working condition the expansion operation in vertical and horizontal holes respectively. The Hydraulic force acted on the expansion cone is defined and analyzed; in vertical and horizontal wells, the mechanical behaviors and movements of the expansion tools are researched respectively. In the analysis, the compression stress in the hydraulic pipe is bad for the operation. For decreasing the compressive stress, a telescopic joint should be connected to the top of the expansion pipe. These researches are conducive for the RD and improvement of expansion tools and expansion process.