Abstract: The regulation of hydration phenomenon on clay mineral surfaces is the key to improving the efficiency of coal resource utilization and coal slime water recycling in China. This study focused on the major clay mineral in coal preparation-kaolinite and explored the influence of solution conditions on the hydration characteristics of three different kinds of kaolinite surfaces using the atomic force microscope colloidal force measurement-force fitting method based on EDLVO theory. The results showed that the surface hydration force constant of kaolinite is independent of the chemical composition of the mineral surface, and it is independent of solution pH, while the attenuation length presents a trend of Al basal plane > Si basal plane > edge surfaces. In this research system, it was found that the hydration force can be superimposed on the DLVO force, and a theoretical interaction energy calculation model for the potential self-assembled structures of kaolinite was established. Through analyzing the interaction energy of different association structures of kaolinite, the optimal solid-liquid separation conditions was predicted to be pH 5, and it was visually comfirmed by macroscopic kaolinite suspension settling tests. The findings of this study provide a theoretical basis for solid-liquid separation of coal slime water.