Abstract: In order to simulate 3-D initial geostress field accurately and lay a foundation for the following numerical analysis of underground engineering, a new method was put forward to simulate geostress in ANSYS only by setting poisson’s ratios in three orthogonal directions of formation through assuming the formation as the orthogonal anisotropic material and using its elastic constitutive relation. The results show that the geostress distribution simulated by the new method coincides with the theoretical values well; the initial displacement eliminated by the equivalent node reaction force balance method is below 10-15 m, which could meet the accuracy requirement; when the formation material is elastic, this method is applicable to all common elements, however, when the formation material is elasticoplastic, such as DP material or bilinear kinematic hardening material, only partial elements like SOLD45 are applicable. Overall, the new method avoids the complex programming process in the conventional simulation and has good feasibility and high accuracy.

Key words: poisson&rsquo, s ratio