Abstract: In order to research the interaction between deep rock of lower coal seam floor and water in Jibei Mining Area, the two different types of rocks from Daizhuang Coal Mine are carried out continuously test between rock conductivity and its mass loss rate in condition of purified water for 57 days. The results show that the changes of conductivity of different rocks follow certain rule in purified water that tend to statistically increase with time going, and all rocks follow similar rule. There exists positive relevance between rock conductivity and its mass loss rate.