A series of PIM-1/POSS microfibrous membranes were fabricated by electrospinning technology. The addition of POSS particles could greatly enhance the hydrophobicity, and a superhydrophobic-superoleophilic membrane was obtained as the POSS concentration increased to 40 wt %. The scanning electron microscopy images indicate that the incorporation of POSS particles results in formations of hierarchical structures on the surface of the PIM-1/POSS fibers. Both the intrinsic hydrophobic nature of FOSS and the increase in the fiber surface roughness led to the sup erhydrophobicity and superoleophilicity. The 40 wt % PIM-1/POSS fibrous membrane could not only separate a wide range of immiscible oil water mixtures with efficiencies higher than 99.95% but also separate water-in-oil emulsions with efficiencies higher than 99.97%. Furthermore, because of the ultrahigh intrinsic microporosity of the PIM-1 polymer, the PIM-1 fibrous membrane exhibited the ability to adsorb a large amount of contaminants such as oil red 0 and solvent blue 35 from oils. Therefore, these membranes are multifunctional and can be applied to treating immiscible water oil mixtures, water-in-oil emulsions, and cleanup of oil soluble contaminants.