Abstract：The in-situ stress of rock mass is determined by Kaiser effect of rock under uniaxial compression. This method is applied widely in rock mass engineering. Based on the recent in-situ stress field by Kaiser effect，direction of modern in-situ stress field，direction of in-situ stress in the location of samples and in-situ stress in the three directions are presented by Kaiser effect of rock under uniaxial compression and micro-fault research methodology in Qinling area along Xi¢an－Nanjing Railway. Modern in-situ stress field is in the direction of northeast，and the in-situ stress gets up 15 MPa. The results by Kaiser effect are consistent with those of field test.
