Polymers of intrinsic microporosity (PIM) are one of the potent materials for gas separation.PIM membranes,especially PIM-1 membranes,due to their highly twisted ladder-like structure,often possess high permeability and low selectivity.In this study,novel CO2-philic PEG-POSS nanoparticles were incorporated to prepare PIM-1/PEG-POSS Mixed Matrix Membranes (MMMs).The MMMs were characterized by Fourier transform infrared (FTIR) spectra,thermal gravimetric analysis (TGA),X-ray diffraction (XRD),transmission electron microscopy (TEM) and scanning electron microscopy (SEM).Single gas permeabilities of N2,CH4 and CO2 were measured by the time-lag method.CO2 solubility coefficient slightly increased and the selectivity of CO2/CH4 and CO2/N2 were significantly improved as a result of favorable dipole-quadrupole interaction between CO2 and PEG-POSS.Optimal performance of PIM-1/PEG-POSS (10) showed CO2 permeability higher than 1300 barrer.And the selectivity of CO2/CH4 increased from 12 to 30 and the selectivity of CO2/N2 increased from 19 to 31 compared with pristine PIM-1.The separation performance of CO2/CH4 in PIM-1/PEG-POS S (10) surpassed the Robeson upper bound in 2008.