Abstract: The foundation pit of Gezhouba Dam at the part of Erjiang River was discovered to remove in surrounding rock during excavation. For the purpose of ingestigation of its causes, a fabric analysis method is adopted in this paper. The occurrence of each fabric factor can be accurately measured and calculated by the mathematical statistics, so as to analyse the formation conditions of rock and the genesis and development of various tectonic movements. The orientation and magnitude of rock stresses are studied due to changes of crystal lattice of rock-forming minerals caused by differential movements inside the rock. Twelve pieces of sample which were cut off from the original rock as the Dam site were fabrically analysed respectively by X-ray method and microscope (F fabric) method. By comparing with each other, the orientation and magnitude of the tectonic stresses were obtained. It is shown that the orientation and magnitudes of in-situ geo-stress as determined from the fabric analysis are in accord with the results obtained from engineering geology or in-situ stress measurement. From this research, the orientations and magnitudes of geo-stress determined by the fabric analysis are found to be ;suitable for evaluating stability in rock engineering.