Abstract: Cataclastic rock mass has dominant discontinuous medium features. There are a special rock mass along with reconnaissance and building of Hydropower in the west. The rock mass should be cataclastic rock mass because of small space between discontinuities. But the rock mass differs from the common cataclastic rock masses because it has high mechanical characteristics and likely continuous medium features. The rock mass has high modulus of deformation, high shear strength and high sound degree coefficient. It is hoped to have reference to other projects. Two examples are analyzed. A new method of available rock mass in hydropower project is obtained.