CO₂ flood had been used successfully to recover crude oil from reservoirs over 60 years. Theoretically microscope displacement efficiency was approaching 100%. However, low viscosity and density of CO₂ compared with crude oil and reservoir heterogeneity resulted in viscous fingering and gravity segregation, which caused poor sweep efficiency. Different methods of mobility control in foreign countries were reviewed including water-alternating-gas, direct thickening CO₂ by polymer, CO₂-foam flooding, combined gas with chemicals and gas assisted gravity drainage. Other methods about improving sweep volume had also been introduced briefly. Mechanisms of these methods and their advantages and disadvantages were analyzed. The goal was to gain advanced approaches and experience for further improving sweep volume for CO₂ flood in China.