Abstract: High-water-content material stone serves as one of the filling materials in the underground goaf, its moisture content has a distinct impact on the deformation and failure character of the stone. The internal material structure was analysed by XRAD and SEM. The MTS was used to test the compression deformation failure character with different moisture content. The results show that the stone had a poor weather resistance, which makes it fit to use for damp closed mine; The tighter the structure of ettringite molecular was, the lower moisture content was and the less internal space and deformation were. The material presented plastic failure characteristics, whose longitudinal deformation was big and transverse deformation shrinked due to water of compaction. When the moisture content of stone increased, the elastic modulus and deformation modulus was reduced, moisture content increased by 6 percent, the elastic modulus reduced about 50 percent. Poisson's ratio remained unchanged with the moisture content change.