According to the situation on back-salinity at clay interlayer in Gansu Shule River irrigation area,the improvement technology on drainage salinity through stand-hole was suggested to adopt in Shule River irrigation area.

This paper deals with the effect on infiltration process of clay interlayer in sand by lab experiments on water infiltration into sand column that contains a clay interlayer.

Through the analysis of the variation of underwater level,pore pressure and the technology parameters,the mechanism on this new method applied to the dredger fill with soft clay intercalation was discussed.