The invention discloses a water-absorption flame-retardant sponge and a production method, which is characterized in that the sponge comprises the following raw materials by weight: 95-110 parts of propylene glycol block polyether, 48-55 parts of toluene diisocynate, 8-10 parts of polyacrylamide, 5-6 parts of antimonous oxide, 0.5-0.75 parts of triethylamine, 3-4 parts of dichloroethane, 3.5-5.5 parts of zinc oxide, 4.0-5.0 parts of glycerol, 0.5-0.7 parts of antioxidant 168, 0.3-0.8 parts of dibutyl tin diacetate, 0.3-0.5 parts of sodium laurylsulfate, 4-5 parts of modifier and 6.5-9.5 parts of water. The sponge has excellent flame retardant performance, water absorption performance, mould resistance and air purification, nano calcium carbonate in the raw materials has a three-dimensional structure, and has good dispersibility, can enhance the hardness of the sponge, and antimonous oxide has good flame retardant effect.