Abstract: As a key procedure of preparation of backfill slurry,the tailings thickening has hence been treated as a re- search focus. Many practical results including the thickening mechanism of tailings tank and principles of selection of flocculants have already been obtained. However,the mechanism studies of the hindered settling of tailing particles have been lagged,resulting in lacking empirical or theoretical calculation models,which will restrict the high efficient thickening of tailings and the precise control of preparation of different tailings slurries. Therefore,to further study the insuffi-cient aspects of aforementioned researches and to gain the features of the hindered settling of backfill tailing par-ticles,by using the classified and fine tailings from a real mine,the hindered settling experiments with the different contents of tailings and concentrations have been carried out. Based on Kynch theory,the experimental results have been fitted to describe and demonstrate the applicability of Richardson-Zaki theory and Selim theory in calculating the hindered and polydisperse settling of tailing particles. The fitted results show that the R-square figure between the cal- culated settling rates based on Richardson-Zaki theory and the experimental results is over 0. 87 and there is no obvi- ous relations among the residual errors,which proves the applicability of Richardson-Zaki theory. Comparing to the val- ues calculated through Richardson-Zaki theory,the results based on Selim theory are closer to the real ones of polydis- perse settling,which means Selim theory can represent some features of polydisperse settling,namely the velocity de- crease features caused by the interactions of tailing particles and can be utilized as a reference in tailings thickening. Furthermore,to clearly explain the mechanism of hindered settling process,the effects of PSD of tailings on hindered settling and its mathematical expression and the mechanism of interactions between coarse and fine tailings in this process will be studied in the future.