Composite hollow fiber membranes were prepared by a dry-jet wet spinning process using a double layer spinneret. These membranes were composed of a thin and dense outer-layer of poly(ethylene oxide)-containing polyimide and a sponge-like inner layer of other polyimide. The outer layer was responsible for the separation and fabricated as thin as 1μm. The permeation flux of CO 2 , R C O 2 , and the CO 2 /N 2 selectivity decreased 40% and 10-20%, respectively, in a month after the membrane preparation. The steady performance was still high; for example, R C O 2 =69 10 - 6 cm 3 (STP)/(cm 2 s cmHg) and the selectivity of 33 at 323K.