Abstract: This paper summarizes and defiene the structure technology terms and concepts.They are used for investigations and study of rocky slopes at present. The notion of slope mass based on the stability evaluation of slope is put forward. Then, a classification system of slope mass structure was summarized and put forward. This system is based the rocky slope investigations in the field of Chinese hydropower project in recent years. It includes the controlling structural plane and potential deformation and instability model. With this system, rocky slopes could be divided into four main types and nine subtypes. The four main types include bedded slope mass structure, middle-steep joints (or joints surfaces) controlling slope mass structure, wedge-shaped slope mass structure, and homogeneous slope mass structure. This kind of slope mass structure notion and classification system has directive significance to qualitative evaluation for the stability of complex rocky slope, the selection of calculation method, the determination of boundary condition, and the establishment of scheme controlling stability.