The mixture of ionic liquid (IL) and zeolitic imidazolate framework (ZIF) was proposed for CO capture by adsorptive absorption. The IL ([BMIM][BF4], 1-butyl-3-methylimidazolium tetrafluoroborate) and ZIF-7 or ZIF-8 served as absorption and adsorption functions, respectively. The solubility of CO in single [BMIM] [BF4] and in the [BMIM] [BF4] + ZIF-8/ZIF-7 mixtures at different compositions were measured at temperatures (298.2, 288.2, 273.2, 258.2, and 243.2 K) and pressures up to 3.50 MPa. The results show that the addition of ZIF into IL can obviously increase CO solubility, and the enhancement effect of ZIF-8 is stronger than that of ZIF-7. Moreover, the UNIFAC model and GCMC (grand canonical Monte Carlo) simulation were used to predict the solubility of CO in [BMIM] BF4] and in ZIFs, respectively. Furthermore, the lever rule combining the UNIFAC model and GCMC simulation together was used to predict the CO solubility in the IL and ZIF mixtures. The predicted results agree well with experimental data, indicating the applicability of predictive model established in this work for IL-ZIF-CO systems.