Abstract: Based on the underground structure scheme of Langyashan hydro-electrical project,lots of elastic-plastic numerical analysis was conducted considering modulus of deformation,layout depth of underground opening,height of main factory and coefficient of lateral pressure as the mainly mechanical parameters that influenced the stability analysis of underground caverns.The statisticsal method was employed to investigate the variation of displacement of surrounding house and the forecast model was found.Then the forecast model was used to analyze the sensitivity parameters.It was shown that there was good agreement between theoretical result and monitored result.