Abstract: The mechanical and deformation properties of soil-rock mixtures with different water contents are essential for landslide evolution and stability studies. This study investigated the shear mechanical and deformation characteristics of soil-rock mixtures with different water contents using a large direct shear apparatus with a particle image velocimetry(PIV)system. The results showed that the shear strength of the specimen first increased and then decreased with increasing water content. The lubricating effect led to a decrease in the internal friction angle when the water content exceeded the optimum water content. The cohesive force also decreased substantially when the water content approached the saturated water content. The shear band and shear influence zone appeared at a specific shear displacement during shearing. The shear influence zone gradually disappeared as shear displacement continued to increase. When the specimen had the optimum water content, the shear influence zone area was more prominent due to the noticeable cementation effect, and the stress release range was extensive. The entire shear evolution process of the specimen can be analogized to a push-type landslide or a pull-type landslide. The results provide an essential reference for understanding the strength change and deformation evolution of soil-rock mixtures.