Abstract: In order to research the laws and characteristics of water-rock interaction of deep mudstone in different solution, we took the deep floor of Yongcheng Coal Mine as the research object, and put them into distilled water, tap water and mine water, and conductivity test were measured at the same time; on the basic of that, we analyzed the difference of water-rock interactions of this mudstone in different solution by means of disintegration, fluorescence, X ray diffraction and SEM, etc. The results show that: the change of electrical conductivity in different solution is different, and dry-wet process has a significant effect on the water rock interaction; the mudstone is mainly composed of quartz, mica, chlorite and it is hard to be disintegrated; the influence of mudstones soaked in different solution on the microstructure of mudstone is different; the mine water with high degree of mineralization made the micro structure of mudstone the most loose, then the tap water, and the influence of distilled water is the smallest.