In the process of gas control, the protective layer was set to extract gas in protected seam, and fracture of bottom plate was to be evacuated from the protective layer in mining process. Combining with protective layer conditions in 3527 working face, gas drainage borehole was made. At the same time, the effect of gas drainage was analyzed by parameters of gas concentration and extraction purity, etc. Therefore, this method was determined and it had obvious effect on control coal gas in lower coal seam.