Based on large mining height fully mechanized working face driving speed influence to stratum key seam cantilever beam collapse and mine pressure， through working face key seam long cantilever beam and short cantilever beam- masonry beam， the two structure influence mechanism to working face mine pressure and the analysis and verification of 1611（3）large height fully mechanized working face mine pressure measured data in Zhangji Mine， key seam cantilever beam collapse strata behavior under different mining speed was found out， in the low mining speed， key seam 1 and key seam 2 broke and overlapped， which led the fierce pressure of the working face and difficult support， improving the mining speed appropriately could avoid the two key seam breaking simultaneously and reduce the pressure strength.