The invention relates to high-value cycling and reusing techniques of waste polyester and particularly relates to a method for preparing a high-quality fusant from waste polyester textiles. The method comprises the following steps: adding 1-8% of alcohol into the raw material according to the mass of the raw material, and carrying out blending and melt extrusion by virtue of a screw extruder, wherein the melt viscosity of the fusant from the screw extruder is 0.40dl/g-0.50dl/g; and then adding the material into a tempering and viscosity-regulating device, wherein the melt viscosity of the fusant from the tempering and viscosity-regulating device is 0.620dl/g-0.685dl/g. According to the method, by adding a proper amount of glycol, the melt viscosity is increased, meanwhile, the problems that the cycle of a filter is short, and the maintenance quantity of a vacuum system is great are further effectively solved, the production cost is lowered, and the additional value of products is further increased.