The invention discloses a reduction and recycling method for purified cotton cooking and cleaning wastewater. The reduction of the wastewater is realized by completely separately collecting and reusing the purified cotton cooking wastewater and washing wastewater each time in multiple washing; and in wastewater recycling, a microfiltration membrane, an ultrafiltration membrane and a nanofiltration or reverse osmosis membrane are adopted for treatment, concentrated liquor of the ultrafiltration membrane is added with alkali to form alkali liquor for recycling, the alkali liquor is used for cooking the next batch of materials, concentrated liquor separated by the nanofiltration or reverse osmosis membrane is subjected to subsequent treatment for recycling, and the concentrated liquor subjected to subsequent treatment becomes cooking wastewater for the next batch of materials, effluent separated by the nanofiltration or reverse osmosis membrane is subjected to subsequent treatment, and effluent subjected to subsequent treatment reaches the standard and is discharged. Compared with the prior art, the reduction and recycling method has the advantages that: the total amount of the purified cotton cooking and cleaning wastewater is reduced by over 75 percent, the chemical oxygen demand (CODcr) is reduced by over 70 percent, the wastewater is subjected to subsequent treatment to reachthe first class national standard, and wastewater subjected to subsequent treatment is discharged.