Starting with the production flow of polyester alkali de-weighting products, this article analyzed the parameters and flows of hard-twisted PET woven fabrics, and discussed the effects of different alkali deweighting machines and ways on handle, style and strength of the products. Furthermore, the effect of preshrinking, pre-setting and de-weighting in de-weighting process of hard-twisted PET woven fabrics was investigated especially. Finally, it was pointed out that computer control in dye machines during the preshrinking and de-weighting process is crucial to ensure the quality of products.