The invention relates to a resourced recovering and utilizing method for waste cotton fabric, in particular to a technology for recovering polyester and cotton fiber from waste polyester cotton blended fabric and using the polyester and the cotton fiber during the production of fermentable sugar, and belongs to the field of resourced cycling and reutilizing of solid waste. According to the resourced recovering and utilizing method, concentrated phosphoric acid is used as a solvent, a reaction is conducted under the conditions that the mass fraction of the phosphoric acid is 82 to 86 percent, the solid-liquid ratio is 1:10 to 1:30, the reaction temperature is 45 to 60 DEG C, and the reaction time is 2 to 18 hours; the cotton fiber in the polyester cotton blended fabric is completely dissolved, so as to enable the polyester to be isolated and recovered by one hundred percent; then water is added to a solution to dilute the solution, so as to enable cellulose to be regenerated and obtain regenerative cellulose with a low cleanliness degree and a low polymerization degree, which is applicable to enzymatic hydrolysis; and after the regenerative cellulose is subjected to the enzymatic hydrolysis, the fermentable sugar is generated to be used as a carbon source for fermenting and producing bio-based products. Waste liquid is distilled and the concentrated phosphoric acid is recovered to be circularly used. The resourced recovering and utilizing method is applicable to the polyester cotton blended fabric formed in any proportion, has the advantage of relatively low energy consumption and is simple to operate; and the polyester can be recovered by one hundred percent, the concentrated phosphoric acid can be simultaneously recovered to reduce costs, and the cotton fiber component is utilized to produce bio-based sources or bio-based products.