In order to make a microfiber fabric with PET/Co-PET Sea-Island Type microfiber, the optimum condition of extraction and elimination of Co-PET from the mocrofiber was examined. At the same time, the physical property change of the fabric with respect to the change of the relative amount of the Co-PET in the microfiber was also examined to provide a directly applicable data set to the industry. The sample fabric used was warp 75/36(DTY) and weft 0.05d(PET/Co-PET, Sea Island Type Microfiber) twill fabric of 36 separated yarns＋40/24(high shrinking yarn) with 130/48 ITY. The data set was made at various NaOH concentrations and steam temperatures with time as a main variable. The physical properties examined were the tensile properties. The results obtained were the tensile. The results obtained were 1. For a proper extraction of Co-PET (13.5%)from the microfiber with wet curing, it takes more than 5 min. in 8 and 12% of NaOH solutions but it takes only 3 min. in 18% of NaOH solution at 12$0^{circ}C$. 2. For a proper extraction of Co-PET (13.5%) from the microfiber with wet curing, ti takes 3~5min. in 12 and 14% of NaOH solution and it takes less than 3 min. in 18% of NaOH solution at $130^circ{C}$. 3. The increasing ratio of WT increased with increasing NaOH concentrations and the equilibrium point reached was 3 min. at $120^circ{C}$. 4. The WT increasing ratio was greater in 14 and 18% NaOH solutions than in 8 and 12% of NaOH solutions at $130^circ{C}$5. The RT ratio changes at $120^circ{C}$ in 8 and 12% of NaOH solutions were indifferent from that at $130^circ{C}$ in 12% of NaOH solution. However, the RT was apparently decreased with increasing NaOH concentration.