The invention discloses a graphene, silver phosphate and titanium dioxide dual-functional composite and a method for preparing the same, and belongs to fields of photocatalysis technology, biological antibiosis and water pollution control. The method includes steps of ultrasonically treating oxidized graphene in water to obtain oxidized graphene dispersion liquid; dissolving silver phosphate in deionized water, adding the deionized water with the silver phosphate into the oxidized graphene dispersion liquid under the condition of stirring, and then stirring the oxidized graphene dispersion liquid to obtain mixed solution A; ultrasonically dispersing P25 in deionized water to prepare dispersion liquid, dripping the P25 dispersion liquid into the mixed solution A under the condition of magnetic stirring, and then stirring the mixed solution A to obtain mixed precursor solution B; and dripping phosphate solution into the mixed precursor solution B, then continuing stirring the mixed precursor solution B, shifting the mixed precursor solution B into a hydrothermal reaction kettle to enable the mixed precursor solution B to react so as to obtain a product, cooling the product to the room temperature, centrifuging the product, then washing the product and performing vacuum drying for the product to obtain the composite. The prepared composite not only can quickly degrade organic pollutants with certain concentration when irradiated by visible light, but also has broad-spectrum and efficient bactericidal activity for various bacteria.