In order to study microscopic displacement effect of hot water flooding on heavy oil qualitatively and quantitatively，a new method for displacement effect analysis was established which is named as“Cutout-Flatten Image”method. In oilwet micro-models，hot water flooding of heavy oil was performed separately at 75 and 90 ℃. The variation characteristic and mechanism of micro sweep efficiency，displacement efficiency and recovery efficiency were analyzed comparatively. Experimental data show that micro displacement effect is improved greatly by emulsion entrapment and emulsion entrainment in the oil-wet models. Micro sweep efficiency，displacement efficiency and recovery efficiency of hot water flooding at 90 ℃ for heavy oil are all higher than those at 75 ℃. Water-in-oil emulsion is in a few of residual brown oil films in the oil-wet micro-models. The residual oil in the swept area of hot water at 75 ℃ is large in quantity with a net-and block-shaped distribution；while that at 90 ℃ is small in quantity and it distributes in the shape of isolated island with poor continuity.