Abstract: In order to investigate the main impact factors of water absorbability of rock of coal-bearing strata and the relationship between them, rock samples were taken from coal-bearing strata in Hanglaiwan coal mine, according to the water physical and X ray diffraction experiment data of the rock sample, the factors of water absorbability of rock were analyzed through grey relational analysis and stepwise regression analysis. The results show that porosity and content of illite, kaolinite, K-feldspar, chlorite, plagioclase feldspar are the main impact factors of water absorption of rock. And a regressive equation of water absorbability of rock was set up, which could show the quantitative relationship between the water absorbability of rock and the main impact factors in the mining area.