Abstract: The effect of grouting reinforcement of floor is closely related to geology, hydrogeological condition and grouting engineering of the working face. Taking the 14141 working face of Jiulishan coalmine in the typical water-abundant Jiaozuo mining area as engineering background, this paper statistically analyzed the geological and hydrogeological information and parameters revealed by a large number of floor grouting boreholes, evaluated the conditions of grouting reinforcement, and further provided a method to assess the grouting effect. The conclusion of research showed that the water abundance in the floor was partitioned according to the water inflow in the grouting boreholes, based on which the positive correlation between the water inflow and water pressure was obtained. It was shown that the water abundance in L8 limestone aquifer was weaker than that of L2 limestone aquifer by analyzing the outflow frequency and total water volume in different depth, and impact of faults on water abundance in the floor and grouting effect was significant. By analyzing the dynamic relationship among water inflow, water pressure and grouting volume comprehensively, it was found that the water pressure was kept increasing as the grouting continued, which reflected that the fissures in the underlying strata were effectively grouted, and increased local tightness of aquifer. The results indicated low water pressure, low flow rate and low grouting volume were the signs of ideal grouting effect.