Abstract: Due to the reasons of preferential exploitation of protective layer, production water and karst fissure water in coal seam geology, a large amount of water is pooled in the goaf of the overlying coal seam in the mining process of the close coal seam, while the mining of the underlying coal seam will perform secondary pressure relief on the overlying rock. Lead to overburden rock under the condition of hydraulic fracture cross fall pattern, to strength, to step distance is different from the characteristic parameters such as pressure is not affected by hydraulic condition of working face, therefore in this paper, the theoretical analysis, analog simulation and numerical simulation study the research method of combining under the influence of hydraulic conditions was analyzed v in the process of the coal bed mining strata fracture dynamic evolution rule, The influence of hydraulic conditions on overburden straddling and mining-induced fracture development is pointed out. The results showed that: Upper strata across the fall the process of mining face and evolution law of mining-induced fractures is not affected by hydraulic conditions, but under the influence of hydraulic conditions first weighting interval of overburden rock decreases 10 m, the periodic weighting interval decreases 3 m, and the mining face the same distance influenced by hydraulic conditions of caving of working surface rock strength is relatively severe, Its displacement and compressive strength are also relatively large, so the support strength or density should be increased when supporting the overburden of working face.