Abstract：In order to investigate distributions of in-situ stress in No. 3 coal seam of southern Shizhuang block, southern Qinshui basin and determine influences of the stress on permeability, the superposition area of the coal seam folds was divided based on characters of paleo tectonic stress field of No. 3 coal seam. Hydraulic fracturing method and acoustic logging were adopted to obtain the stress data. Coal reservoir permeability was obtained by using the measured and geological strength index ( GSI) . The regression analysis was carried out to find out relations between the present stress and depth of coal seam. The effect of the present stress on the permeability of coal reservoir was summarized. The results showed that the principal stress linearly increased with depth. When the burial depth of coal reservoir was lower than 700 m, the present stress state showed σV> σH>σh. The stress state was the static field. When the burial depth was between 700 and 900 m, the present stress showed σH≈σV≈σhand the stress state was quasi-hydrostatic. When the depth is more than 900 m, the present stress showed σH> σV> σh. The stress state was the static field and the maximum horizontal principal stress was dominant. For the same tectonic site, the coal present stress and buried depth had a good negative exponential relations. When there was no multi period structural superposition, the relations between present stress and permeability was not significant. While structural stage was considered, the relations between the stress difference and the permeability in the same superimposed area was exponential relation.