Abstract: A large model was used to simulate the effects of terrain, physiognomy etc. to original ground stress.A small model,in which the mesh was refined, was used to precisely simulate excavation of the underground powerhouse. The displacement boundary of the small model used the result of the large model, which was interpolated with numerical inverse isoparametric mapping. Stability of a ground powerhouse in softhard interlayered rock mass was analyzed with elasticplasticbrittle theory. The effect of replacement of soft rock P31qand Huanglong shear zone was emphatically analyzed, and the layout of the underground powerhouse and replacement of soft rock were suggested. 