Abstract: Using the RFPA-flow numerical simulation software, numerical simulation of overburden caving phenomenon during mining process that overburden strata is away from the roof about 30 m and gas seepage velocity changing laws of the overburden strata with the working face advancing are performed. The analysis results of experiment show that the pressure relief zone, stress concentration zone, pressure stable zone and rock stress zone are formed in front of the working face during the mining process. The weighting step of overburden strata is about 15 m. Gas seepage velocity in the overburden strata presents variation tendency of increasing first, the decreasing later and then increasing.