Abstract: Daguangbao landslide is the largest landslide triggered by the Wenchuan earthquake. The exposed sliding zone with a length of 1.8 km and highly ruptured rock mass is located at the south side of the landslide, which has attracted great attention across the world. To evaluate the strength parameters of cataclastic rock mass in the sliding zone accurately, a detailed field survey work is carried out on the basis of previous researches by using a France Phicometre dual-purpose geotechnical in-situ borehole shear tester to investigate the cataclastic rock mass in Daguangbao landslide slip zone. A comparative analysis among the test results, the values of Hoek-Brown strength criterion and the mechanical parameter values based on the engineering geologic analogy method is performed. Finally, the mechanical parameter values of the rock mass of the Daguangbao landslide of the south side are proposed: its cohesion is from 245 kPa to 480 kPa, and its internal friction angle is from 25.0°to 26.5°.