The shear strength of the rock-soil body， especially the shear strength of the rock body structural plane of the weak layer， plays a vital role in the stable analysis of landslides. The sample was lightly disturbed and the test status was more consistent with the real state of the rock-soil body in the in-situ shear test， moreover， the parameters obtained were more real， which is one of the important methods of in-situ test for landslides investigation. It is suitable for determining the shear strength of the rock and soil structure surface， geotechnical contact surface， sliding surface， mixed soil layer and other coarse granular soil layers. This study takes Chongqing Huayu · Guanlanhuafu project as an example， the original sample was collected for laboratory direct shear test while the in-situ shear tests were made， by which two shear strength parameters under different experiments were obtained. The stability of the landslides under different operating conditions were analyzed and calculated using the above two parameters， and compared with the actual deformation characteristics of the landslide body， thereby the rationality of the rock-soil body shear strength parameter was verified， which can provide reference for similar projects.