Liquid CO2 has similar properties to non-polar hydrocarbon oils and can be used to achieve hydrophobic aggregation separation of coal macerals. To reveal the influence of the water-liquid CO2 treatment on the interfacial properties of vitrinite and inertinite, the effects of the water-liquid CO2 system on the interfacial properties of vitrinite and inertinite were investigated by SEM, BET, FTIR, and XPS. The results showed that the content of oxygen-containing functional groups on the coal macerals were reduced more significant than the hydrocarbons due to the physical adsorption and chemical extraction of liquid CO2, which led to an increase in the hydrophobicity of vitrinite and inertinite. The higher porosity and specific surface area of inertinite causing the decrease in the content of oxygen-containing functional groups in inertinite was greater than that in vitrinite. This study provides theoretical support for the separation of coal macerals using liquid CO2 hydrophobic agglomerates.