Due to good injectivity and high oil-flooding capacity，CO₂ flooding has become a very potential method to enhance oil recovery in low permeability/tight oil reservoir，but due to the reservoir heterogeneity and fractures，gas channeling easily happens during the injection，which affect the development of reservoirs. The CO₂ continuous injection and huff-n-puff experiments were designed and conducted in cores with different permeability contrast，and oil recovery and oil distribution（scanned by CT）was measured as the index to investigate the effect of heterogeneity on CO₂ flooding. The results showed that，during the continuous injection of CO₂，When the permeability of the low-permeability layer was 5.0×10^-3 μm² ，as the permeability contrast increased from 1.0 to 2.2，the oil recovery was significantly reduced from 88.5% to 58.3%；when the permeability contrast further increased from 2.2 to 154.0，the decreasing trend of oil recovery slowed down from 58.3% to 44.8%. The injected CO₂ mainly flowed and displaced the crude oil in the high permeability layer，while the crude oil in the low permeability layer was basically unused，which was the reason why the recovery rate decreases significantly with the increase of heterogeneity. Even if the core heterogeneity was weak，the permeability contrast being of 2.2，which would lead to a significant reduction in oil recover of CO₂ flooding. When the permeability contrast was less than 2.2，the increase of heterogeneity leaded to a more significant decrease in oil recovery. When the permeability contrast was higher than 2.2，the recovery rate continued to decrease with the increase of permeability contrast，but the trend would slow down. After continuous injection of CO₂，the Huff-n-puff was conducted. The oil recovery of heterogeneous core models with permeability contrast of 1.0，2.2，15.5 and 154.0 increased from 58.3%，57.2%，44.8% to 80.4%，75.8%，74.4%， respectively. The oil saturation of low permeability layer decreased significantly，and the crude oil of low permeability layer was effectively utilized. CO₂ huff-n-puff is less affected by reservoir heterogeneity，which is a potential replacement method after continuous injection of CO₂.