Tailings dams and silt dams store a large amount of loose particulate matter or slurry. Landslides or dam failures can result in highly destructive flows of water-soil mixtures or mudflows. The mechanisms of those mass flows are very complex, with rheological properties of the slurry, downstream topography conditions, and dam break volume being key factors influencing the outcomes of dam failure disasters. This study employs rheological tests and small flume dam-break physical model experiments to investigate the flow patterns and characteristics of different particle-sand mixed dam-break slurry on slopes. The results indicate that fine-grained water mixed slurry behaves as a viscoplastic fluid, with its constitutive relationship aligning more closely with the H-B rheological model. Coarse-grained water mixed fluid is a two-phase flow, forming a deposit with a scouring and deposition structure. Fine-grained water mixed fluid is a pseudo-one-phase flow, forming a fan-shaped deposit. The rapid flow velocity on the slope is directly related to the concentration of the slurry, with lower concentrations resulting in faster movement speeds.