Abstract: Gradual receding landslide often happens at Heifangtai terrace due to groundwater level rise. The loess at the trailing edge of the landslide is in a saturated state with a water level rising. In order to study the permeability change under soaking, the variable head permeability test was carried out on the remolded loess, and the microscopic change of permeability under the soaking of Heifangtai loess was studied by laser particle size analysis, electron microscopy, water chemistry test and PCAS. The permeability of the remolded loess would significantly decrease under soaking, because the coarse particles transform into fine particles after loess soaked, the gaps of coarse particles were filled and the pores in the loess reduced. The dissolution of the soluble salt increased the concentration of Na+ and SO42-. After saturation of water, the loess microstructure was destructed, and soluble salt was dissolved. Loess particles lost cohesion partially and were compacted under water infiltration effect, which make the permeability of loess decreased. Generally, the attenuation of permeability can be summarized as the action of loess particles change and the dissolution of soluble salt.