In this work，molecular simulation was introduced into the design of molecular structure and the study of mixing mecha-nism of miscible flooding agent，which partly solved the problems of long-time and high-cost of slim tube experiments. First，the structures of five types of functional groups with mixed-phase potential were initially identified，and the affinity of each type of functional group for CO₂ was judged based on quantum mechanics by using the electron transfer in the process of electron density and Fukui function studies as well as the energy change in the process of adsorption reaction energy and frontier orbital studies. The molecular structure design of the amphiphilic miscible flooding agent was carried out based on the full consideration of the number of functional groups and spatial site resistance. Based on molecular dynamics，the interactions and dispersion aggregation of the three miscible flooding agents，simulated oils and CO₂ were investigated，and the mixed-phase ability of the miscible flooding agent，was comprehensively evaluated in combination with the diffusion coefficient. The results showed that increasing the number of CO₂-philic groups synergized with the appropriate spatial site resistance was beneficial to enhance the miscible flooding effect.