Abstract: In view of the problem that the coal seam will have stress concentration, longitudinal compression deformation, gas content and pressure increase in the area of pressure relief blind zone, which will lead to some safety hidden troubles in the coal seam mining, the technology of no coal pillar for protective layer of semi coal rock is proposed to realize the comprehensive pressure relief of the lower protected coal seam. Through the theory, this paper analyzed the mechanism of eliminating the blind zone in the upper protective layer without coal pillar mining. Based on this, an on-site industrial test was conducted on 22201 working field of Shaqu Coal Mine, and the test results showed that through the no coal pillar mining of semi coal rock protective layer, the overall pressure relief and permeability improvement of coal seam group with low permeability and high gas outburst are realized and the underlying No.3+4 protected layer gas is pre-pumped with a net volume of up to 18 m³/min, and the concentration is as high as 90%, which shows that the gas control effect by adopting the no coal pillar mining technology system for semi coal rock protective layer has a significant effect.