In order to reduce the miscibility pressure between CO2 and crude oil and improve the oil displacement efficiency of CO2 miscible flooding，three methods to reduce the miscibility pressure were summarized，including miscible solvent，supercritical CO2 microemulsion and CO2-soluble surfactant. The structure characteristics of CO2-soluble surfactant and its mechanism of reducing the miscibility pressure of CO2 were analyzed. The miscible solvent method required a large amount of hydrocarbon gas and the cost was high. Supercritical CO2 microemulsion method could reduce the miscibility pressure to a certain extent，but the degree of reduction was relatively low. CO2-soluble surfactant could dissolve in CO2 so that CO2-soluble surfactant could act on the oil and gas interface，reduce the interfacial tension of oil and gas，and reduce the miscibility pressure. However，there were few kinds of CO2-soluble surfactants at present. Therefore，it was urgent to develop new CO2-soluble surfactant to improve the miscibility of CO2 and crude oil，and achieve high efficiency development of CO2 miscible flooding for crude oil.