CO2 flooding technology serves as an important means of enhanced oil recovery (EOR), capable of significantly improving oilfield development efficiency while achieving geological storage of greenhouse gases. However, the high minimum miscibility pressure (MMP) limits the widespread application of this technology in reservoirs. This paper systematically reviews the latest research progress of chemical miscibility enhancers. Based on their action mechanisms and molecular structures, miscibility enhancers are classified into five categories: hydrocarbons, alcohols, surfactants (including hydrocarbon-based, fluorocarbon-based, siloxane-based, and composite systems), microemulsions, and bio-based types. The action mechanisms, molecular design strategies, and key influencing factors of various miscibility enhancers are analyzed in detail. The effects of different injection methods on miscibility enhancement are summarized, and recommendations for future research directions are proposed. This paper provides systematic theoretical guidance and technical references for the optimization of CO2 flooding technology and the development of efficient miscibility enhancers.