Carbon dioxide oil recovery was developing rapidly in recent years due to the global warming and the resulting requirement of carbon emission reduction.This enhanced oil recovery(EOR)technology is not only suitable for the general oil reservoirs,but also for the low and ultra-low permeability reservoirs. Carbon dioxide miscible flooding can enhance oil recovery efficiently.However,it is hard for most Chinese reservoirs to achieve CO_2 miscible flooding because of the high minimum miscibility pressure(MMP).The methods of lowering the MMP of CO_2 flooding,such as changing the formation temperature or injecting low molecular weight hydrocarbons,alcohols,tall oil or surfactants were reviewed.The characteristics of each method were discussed in detail and the new direction of the technology of CO_2 flooding was pointed out.