The paper focus on the classification rockmass surrounding the Xiaolangdi underground powerhouse. Two rock mass classification systems

RMR and Q

have been used to classify the rockmasses surrounding the underground powerhouse. The supporting measures are suggested based on RMR and Q classifications. The shear strengths and deformation moduli of the rockmasses have been estimated based on the rockmass classification. The monitoring result shows that the underground powerhouse is under the situation of safety.