Abstract: Underground houses are mostly used in the construction of hydropower station, and the deformation characteristic of the surrounding rock is a key problem in the design and construction process. By using the FEM soft and the orthogonal experiment, the influence of multi-factor changing was taken into account, to study the influencing degree of the deformation characteristic of the surrounding rock by each factor, and the order of the influencing degree was listed. From the results we can see, the biggest influencing factor of vault displacement were the thickness of the rock stratum and the depth of the underground house, and the centre of the left side wall were the height and the depth of the underground house, the center of the right side wall was the depth of the underground house. The position of the biggest deformation was mostly near the centre of the left side wall. The biggest influencing factors of biggest displacement were the thickness of the rock stratum, the depth and the height of the underground house. At last, the influencing trend curves of the factor for the displacement of specific position were drawn.