In this work, the density distributions of carbon dioxide around different ionic liquids are calculated using the three-dimensional reference interaction site model integral equation. According to the density distributions, the corresponding excess adsorptions are calculated to estimate the solubilities of carbon dioxide in these ionic liquids. Some predicted results are in good agreement with available experimental data, showing that the structure descriptions are accurate and the direct correlation of solubility with structure is reasonable at low temperature and pressure. As a result, the present theoretical model provides a simple and efficient tool to evaluate dissolving capacity of ionic liquids and their mixtures.