Abstract: In order to analyze the water-rock interaction in the deep “Ordovician Limestone Groundwater” and explain the hydrogeochemical evolution, the hydrogeochemistry simulation of Ordovician limestone groundwater in Yanzhou Coalfield was finished, based on choosing the reaction paths by an integrated approach of water flow and geochemical field. The simulation results showed that: the calcite and dolomite tended to precipitate; the gypsum, anhydrite and halite were unsaturated and tended to dissolve in groundwater; the major water - rock interactions are the dissolution of dolomite, anhydrite and halite, calcite precipitation, cation exchange, and dissolution or escape of carbon dioxide, and the results are very consistent with the qualitative analysis; the dissolution of the mineral phases containing Ca, Mg, Na, SO4 and Cl in “Ordovician Limestone Groundwater” occurred, and the dissolution rate was greater than the precipitation rate.