The changes of weight, breasking strength, handle, molecular weight and crystallinity were investigated when polyester fabric was treated with sodium hydroxide solution. The results are as follows. 1) According to the increases of treating sodium hydroxide concentration, time and temperature, weight and breaking strength loss are increased but handle is improved, and these effects are increased by conjunct treatment with carrier. 2) Molecular weight is decreased by alkali teatment. 3) The change of crystallinity by alkali treatment is not app eoiable.