Based on feature and law of gas emission, as well as low concentration and large volume problem of upper coner gas, gas extraction system with mass flow and low negative pressure was adopted to reduce gas mining space. According to high gas concentration and big storage of high hole ( upside caving zone ), drainage drilling of this coal seam, unloading drill wear layer and so forth, pump and pipeline extraction gas of split source, different subsystem, negative pressure were achieved. Furthermore, seam gas pressure and content were decreased with this effective system. The practice showed that dangerness of coal and gas outburst was eliminated and gas transfinite times during mining period were reduced through implement of gas control technology by sub-source control.