SangZhuling tunnel is the controlling project of the Lasa-linzhi railway engineering, which faces the questions of high geostrss disasters of deep tunnel for the complicated geological conditions. Therefore, the analysis of initial geostress field of the engineering area has important significance to the safety of tunnel construction and the optimization of structure design. Based on the on-site inspection work, the existed geological data in the engineering area was comprehensively analyzed, the theory of Anderson and the engineering analog method were applied to analyze preliminarily the possible values and orientations of the maximum principal stress. The multivariate linear regression method is used to reverse analyze the 3-D distribution of geostress field regime of the whole project area according to the measured geostress dates. The results show that the calculation values fit well with the measured values mostly both in the magnitude and the directions, and the stress distribution is consistent with the regional tectonic background, which indicates that the geostress field obtained by the regression is of rationality and reliability. Finally, the probability and intensity of rock burst along tunnel were forecasted basing on the obtained in-situ stress distribution rule along the axis of the tunnel, so as to provide the basis for later tunnel excavation and supporting structure design.