Abstract：In this work, ultrafiltration- nanofiltration integration membrane technique was applied in alkali reduction wastewater treatment. The results indicated that chemical oxygen demand (COD) of alkali weight reduction wastewater was effectively decreased by this process, and COD removal rate reached over 80%. Meanwhile, the effect of reused wastewater on the polyester reduction process was also analyzed, with main factors, such as temperature, time, alkalinity, and ethylene glycol content (accumulated) discussed in detail. The polyester reduction rate increased with the increase of temperature, process time and alkali concentration. The accumulating ethylene glycol content could also promote the reduction effect of the polyester. The recovery and comprehensive utilization of terephthalic acid, water, alkali and ethylene glycol could be realized by this technique.