One of the key techniques for garbage sanitary burial is the pavement of a liner, which is designed to prevent seepage. It is very expensive. If the aim of paving the liner is turned to " filtration" , we can make full use of the purification or partition capability of the clayey soil to reduce the cost. The term "filtration capability" is a physical parameter put forward to describe the capability of the clayey soil to cut off the pollutants based on the above idea. The following conclusions are arrived at through the study; (1) The filtration capability of the clayey soil can be obtained through experiments and by using some special calculation methods. (2) The more times of leaching of garbage infiltration fluids, the poorer the purification capability of the soil to the pollutants. Also, the purification capability of the soil to the pollutants rises with increasing soil density, and the filtration capability of the clayey soil is lowered with the increasing number of leaching. (3) In the Shijiazhuang area, the purification or partition capability increases rapidly before the soil density reaches a certain value (1. 936 g/cm3) , but obviously slower after reaching the value. This result is of very important application significance in engineering projects. (4) In the soil columns of different densities of the same type of soil, there seems to be a trend of lowering of filtration capability with the increase of soil density.