A novel synthetic process for multi-porous polyimide (PI)/poly (methyl silsesquioxane) (PMSSQ) hybrid material has been studied via supercritical CO2 technology. The end groups of PI precursors were modified by coupling agent to be hybridized with. alkoxysilanes and became PMSSQ precursors. PI/PMSSQ hybrid precursor solution, was spun on a silicon wafer substrate for film formation. The PI precursor segment was imidized and micro-pores were developed by removal of by-product, CO2 via supercritical CO2 media. The PMSSQ precursor segment was cured and nano-pores were generated by supercritical extraction. Average micro-pore size and nano-pore size were 10 mum and 40 nm respectively, The dielectric constant of the multi-porous PI/PMSSQ hybrid film was calculated to 2.5.