In the current classification of rock masses for the building slope engineering, the slope controlled by the outward inclined and weak discontinuity structural plane and one with destruction form of topple are foreclosed and integrity of the rock mass, bond and attitude of the discontinuity structural plane, rock hardness and groundwater abundance are classification factors. The questions for the classification and its application are analyzed. The results show that classification law, classified object and classification factors for the classification are unreasonable, and the classification has no valuable significance.