This paper aims at studying a key technique for how to fix the inner wall that can rapidly and accurately control inter-column void sizeand avoid being disturbed by cutting the soil column during the process of sampling natural soil column using large-diameter lysimeters.And itsystematically proposed the sampling process combined with the practice of sampling natural soil at the Wudaogou hydrological experimentalstation.Besides, it invented the method of the refined soil column of milling cutter and the method of rapid soil cutting of soil cutting knife,whichavoid the problems of rough surface and irregular incision of the soil column brought by using traditional long knife to repair soil manually.Moreover, the methods can reduce the disturbance of the natural soil structure and the boundary effects as much as possible.The experiment hasshown that when the gap between the inner wall of tank and the soil column is 2mm, the natural properties of natural soil can be maintained afterthe operation of lysimeter.Thus,the reality of the lysimeter simulation experiment has been improved.