Abstract: To ensure the safety and efficiency of mining on soft an low permeability flat coal seam with high gas content, we take the X10901 working face in Dawan mine west well as the studying object. In this paper, research was made on stress change law and damage of coal and rock mass and the deformation distribution law of protected seam in upper protective layer mining by using Flac3D numerical software, and carrying out the inspection certification of protective effect on site. The results show that the coal and rock mass around the stope has experienced a transformation from initial stress area to stress concentrated area, depressurized area, stable area and new compaction area in the whole process of excavation. With the advance of working face, the depressurized area which formed by upper protective layer mining is gradually enlarge from “V” type to “U” type. After the protective layer mining, the amount of maximum swelling deformation of protected seam can be 12.2mm (the relative swelling deformation is 4.52‰), and forming the distribution of “three zones” and floor heave of overburden in the vertical direction. Combining with the inspection certification of protective effect on site, protected coal mass has been fully protected after upper protective layer mining. All of these has not only almost eliminated coal and gas outburst danger, but also provided a strong foundation for the high production and high efficiency of mine.