In order to realize the utilization of incineration fly ash （IFA） in asphalt pavement， the IFA was granulated with cement， and silica fume， coal ash. The water stability of asphalt mixture with granulated particles and the influence mechanism of freeze thaw splitting test conditions on its water stability were studied. The results show that after IFA is granulated， the chloride ion leaching rate decrease by about 56.76% and 59.12% respectively. The order of the influence of freeze thaw splitting test conditions on the water stability is vacuum extraction process>freezing process>compaction times. During the process of vacuum extraction， the asphalt film on the surface of IFA/cement granulated particles is destroyed， thus the soluble chloride is dissolved out， the combined action of frost heaving， salt heaving and corrosion of chloride solution in the course of freeze thaw cycle is the key cause of damage to the internal structure of asphalt mixture. The method of co-granulation of cement， silica fume， coal ash and IFA can effectively improve the water stability of asphalt mixture.