To study the microscopic dispersion state of CO₂ in different ester solvents, the solubility, volume expansion coefficients and in situ Fourier transform infrared (FTIR) spectra of the CO₂–ester system were measured. The results show that the solubility and expansion coefficient of CO₂ in ester solvents decreases as the hydrocarbon chain increases. As the pressure increases, the infrared absorption peaks of CO₂ and the functional groups characteristic of ester molecules shift, indicating that CO₂ molecules interact with ester molecules and that CO₂ would destroy the interactions between the ester molecules. The hydrocarbon chain length of the ester molecules has a significant effect on the infrared absorption peak of the CO₂–ester system. As the hydrocarbon chain length increases, the CO₂ absorption peak shift and peak shift of the carbonyl groups in the ester gradually decrease.