Abstract: in-situ stress is the fundamental fore that causes deformation and failure of underground engineering rock mass. In-situ stresstesting technmology plays an important role in safe and efficient mining of coal mines.Basel on the enginering background of No.3 andNo.l5 coal seams in Zhengzhuang Coaul Mine, this paper conducts a theoretical analysis of the magnitude and diection of in-situ stresshased on elastic mechanics and ock acoustic emission Kaiser effect. It uses laboratory tests to sturly the distribution of ground stress, andcompare and verify with field test results. The research resuls show that the vertical stres , the maxinum horizontal principal stres andthe minmimum horizontal principal stess of the No.3 and No.15 coal seams all increase with the increase of the buriedl depth. The in-situstress distribution rules of the two coal seams are very similar and belong to the medium stes area; The maximum horizontal principalsltress of the coal seam> the vertical stress> the mininmm horizontal principal strss , that is， the tectonic stress is grealer than the self-weight stress,which is a typical stress field with tectonic stress ; the direction of the mavinmum horizontal principal stress is relatively stableand is basically concentrated anund N27° W.The ratio of the average horizontal principal stress( the average of the maxvinmm horizontalprincipal stress and the minimum horizontal principal strss ) to the vertical stress of the No.3 and No.15 coal seams roof and floor ae0.968,0.948,0.938,0.934.The natio of the average horizontal principal stress to the vertical stres of the No.3 coal seam is larger thanNo.15 coal seam.The research results provide a certain rederence value and significance for the use of moek acoustic emission Kaiser effectto test in-situ stress.