Abstract: The surface hydration is one of the main reasons for the difficulty of coal slurry water sedimentation and de- watering,the molecular dynamics simulation on the surface hydration of fine slurry particles was investigated in this study using the main fine clay mineral particles ( kaolinite and montmorillonite) in coal slurry water as research ob- jects. The results indicate that water molecules can hydrate on the surface of kaolinite and montmorillonite by hydrogen bonding. The binding force between mineral surfaces and water molecules decreased with the increase of water cover- age (or the number of water molecules),the hydrogen bond at the interface gradually weakened,and the water mole- cules on hydrophilic kaolinite and montmorillonite surface can be gradually formed three water molecules shells,the to- tal thickness is (8 -10) ×10-10 m,and the degree of hydration on different particle surfaces is in order of:kaolinite (001) surface>montmorillonite (001) surface. The effect of divalent metal ions on montmorillonite is stronger than that of monovalent metal ions.