The fluorescent high-polymer composite is a product compounded from a 1*10<-8>-1*10<-4> indolyl cyanine dye, 0.1-10 wt% polyvinyl alcohol and other water-soluble high-polymer substances which account for 0-60 wt% of the polyvinyl alcohol. The physical preparation method comprises the following step: carrying out ultrasonic treatment on the water solution formed by the indolyl cyanine dye, polyvinyl alcohol and other water-soluble high-polymer substances. The chemical method comprises the following steps: converting the indolyl cyanine dye into the succinimide active ester of the dye, and reacting with the polyvinyl alcohol and other water-soluble high-polymer substances, or preparing a film from the polyvinyl alcohol and impregnating the film in the dye succinimide active ester solution. The preparation methods have the advantages of simple preparation techniques, environment friendliness and uniform component compounding. The product has excellent fluorescent characteristic, and is hopeful to be widely used in the aspects of biofluorescence sensors, textiles, medicines, daily supplies and the like.