Abstract: This study is based on the water and chemistry data of Ordovician limestone in different periods of Baode Coal Mine, using ion combination ratio analysis, hydrogeo-chemical simulation, and other methods, the saturation index was calculated by PHREEQC software to analyze the variation of the chemical composition of the ash water in the process. The formation mechanism of the hydrogen sulfide gas in the Ordovician limestone water and the influence of water-rock interaction on the formation of hydrogen sulfide gas were analyzed qualitatively. And the key technologies of hydrogen sulfide gas prevention and control are researched. The results show that from the runoff zone to the stagnant zone, the water chemistry type is HCO3-Na(Na·Ca)→HCO₃·Cl-Na·Ca(Ca·Mg)→Cl-Na(Na·Ca), the overall SO₄²-ion content has a increasing trend, and finally the H₂S gas is formed by the action of BSR. CH₄ and C reduce sulfate minerals to form H2S and simultaneously produce CO₂ and HCO₃-. According to the actual situation of the site, the anti-spray device and the orifice negative pressure pumping device were designed.