The residual oil distribuion becomes complex after surfactant-polymer flooding （SP flooding）. Heterogeneous combination flooding（HC flooding）has the dual functions of profile control and oil displacement，therefore it can be used to employ the residual oil after SP flooding. In this paper，the developed limit of the residual oil at various pore throats was studied by NMR using different-permeability cores，and the CT scanning of the residual oil in the heterogeneous square cores with different permeability ratios through the heterogeneous composite flooding after SP binary composite flooding was carried out. The experimental results showed that the effective producing limitation for residual oil under HC flooding was 0.3—20 μm for the cores with permeability of 1 μm² and 0.2—800 μm for the cores with permeability of 6 μm². CT scanning of heterogeneous cubic cores with different permeabilities showed that the injectivity of viscoelastic particles（PPG）had significant influence on the enhanced oil recovery of the low-permeability zone. If the particle size was compatible with the pore-throat size of the low-permeability zone， the residual oil in the low-permeability zone could be effectively developed by HC flooding，resulting in the enhanced oil recovery by 18.3 percentage point. When the compatibility was poor，the residual oil only in the injection part could be displaced by HC flooding，the performance of profile control and oil displacement of HC flooding was limited and the enhanced recovery rate was only 9.5 percentage point.