The invention discloses a recycling method of waste incineration fly ash. The recycling method comprises the following steps: (1) coating the waste incineration fly ash with calcium carbonate; (2) performing surface modification; (3) evenly mixing the waste incineration fly ash with low-density polyethylene, a lubricant and a compound foaming agent, and performing extrusion palletization to obtain foamed plastic particles; (4) placing the foamed plastic particles in a crusher for crushing to obtain environment-friendly filler. The environment-friendly filler is low in density and light, the leach quantity of soluble heavy metal is small, and the filler can be applied to the plastic industry or SMC industry. The process for preparing the filler from the waste incineration fly ash is free of toxic and harmful waste water and waste gas, the process is short, and industrial production is facilitated.