Abstract: Soil-rock mixture slope is a common type of slope in nature, which has obvious heterogeneity and discontinuity. Rheological property of soil is one of the main causes leading to the soil-rock mixture slope deformation and instability. But almost all the existing analyses on the stability of soil-rock mixture slopes neglect the rheological properties of soil. Using digital image processing technology, a soil-rock mixture slope model in the reservoir area of one hydropower station in China is built. Then the strength reduction method in FLAC^3D code is adopted to analyze the slope stability. The analysis mainly focuses on the creep characteristics of soil and the effect of the creep parameters on the deformation and stability of the soil-rock mixture slope. The results show that the rheological property of soil can obviously reduce the factor of safety of the soil-rock mixture slope, increase the deformation of the slope, and adversely affect the stability of the slope. The creep viscosity coefficient has a great influence on the long-term stability of slope, and the greater the viscosity coefficient is, the lower the safety factor is.