Abstract: Studying the strength characteristics of the accumulation layer in ancient landslides is an important aspect of landslide stability analysis and control. In order to reasonably determine the strength parameters in the stability analysis of ancient landslide accumulation layers, this study focuses on the Jiangdingya ancient landslide treatment project in Zhouqu County, Gansu Province. The study targets the the sliding body soil (gravel soil) and sliding zone soil (gravelly clay) and conducts large-scale field shear tests at two typical sections using the horizontal pushing method. The test results are compared and analyzed with the suggested mechanical parameters based on engineering analogy method. Based on the above research, the following conclusions are drawn: (1) When the shear strain of the sliding zone soil is small, the shear stress-shear displacement relationship curve has crossed, and the shear stress of the soil sample increases with the increase of normal stress and shear strain; (2) The larger the normal stress of the sliding body soil, the more significant the strain softening behavior; (3) The residual strength of the landslide soil has a certain attenuation compared to the peak strength, mainly manifested as a weakening of cohesion, while the internal friction angle remains almost unchanged. This is because the cementitious material in the sliding zone soil is destroyed after shear deformation, leading to a weakening of cementation. The natural residual strength parameters of the sliding body soil on the discharge slope are: the internal friction angle ranges from 18.2° to 24.6°, and the cohesion ranges from 10.2 kPa to 12.4 kPa. The residual strength parameters of the sliding body soil are closer to the values obtained by the engineering analogy method; (4) The recommended values of rock mass mechanical parameters for the sliding zone soil and sliding body soil of the accumulation layer landslide at Jiangdingya are as follows : For the sliding zone soil, the cohesion ranges from 7.0 kPa to 14.8 kPa, and the internal friction angle ranges from 15.0° to 17.5°; for the sliding body soil, the cohesion ranges from 15.8 kPa to 30.9 kPa, and the internal friction angles from 23.9° to 24.4°.