Abstract: In order to study the multifractal behavior during the formation process of ultra-clean coal flocculation through mechanical energy input,the images which describe the generation and fragmentation of flocculation are gathered and analysed. By analyzing the variation trend of the multifractal spectrum and its characteristic parameters, the growth law and the morphology of the flocculation are described.The results show that with growth and fragmentation of flocculation, the morphology of the multifractal spectrum occurs regularity migration, multifractal spectrum width △α which described the distribution uniformity of flocculation shows a trend of first increase and then decrease.The numerical value of △f(α) which described the proportional relationship between the maximum and minimum probability unit of flocculation shows the dominant position of fine particles in the system.The changing trend of absolute value of △f(α) indicates fine particle number and the growth of the flocculation change law.