Abstract: The rheological characteristics and parameters of the filling slurries of 69% to 81% in mass fraction were tested with a four-bladed vane rotary rheometer taking unclassified-tailings filling paste as a research object.Based on the Herschel-Bulkley model,the rheological models were derived from regression at shear rates of 0 to 120s^-1.It is shown that the rheological models exhibit yield-pseudoplastic for the filling slurries of 69% to 81% in mass fraction and Bingham plastic for the filling slurries of 81% in mass fraction.There is a good linear relationship between the flow behaviour index n and the mass fraction of filling slurries,and the flow behaviour index n increases with the mass fraction of filling slurries increasing.Finally,the threshold mass fraction of the paste is 80.91%.