The heterogeneity of the Tahe fractured?vuggy reservoir is strong, and the fluid flow state is complex. The flow and waterflooding mechanisms of high?asphaltene heavy oil remain poorly understood, posing significant challenges to the effective implementation of water injection strategies. Based on a visualization model of fractured?vuggy reservoirs, experimental investigations were carried out on the flow and displacement behavior of heavy oil with different viscosities. The relationship between the flow resistance coefficient of asphaltene containing heavy oil and the viscosity and flow rate was established, and dynamic quantification of oil saturation in different vuggys was achieved through image recognition. The characteristics of waterflooding of high asphaltene heavy oil in fractured?vuggy reservoirs and the influence mechanisms of heavy oil viscosity, fractures, and water injection rate were clarified. The results indicate that the viscosity of heavy oil increased from 59 mPa ? s (medium viscosity) to 1 090 mPa ? s (extra viscosity), the apparent threshold pressure gradient of heavy oil in the fracture cavity increased by one order of magnitude, the flow resistance coefficient increased by three times, and the waterflooding recovery rate decreased by 9.6 percentage points. Increased heavy oil viscosity also reduced the number of vugs affected by waterflooding, thereby increasing the remaining oil volume in attic configurations, localized high points, and along cavity walls. The scale, length, and spatial distribution of crack width have a greater impact on the flow direction of waterflooding heavy oil, and are stronger than the gravity differentiation of oil and water. Appropriately increasing the water injection rate enhances the ability of water flooding to spread and break through small?scale fractures.