Abstract: First, the quantitative characterization of cement paste backfilling (CPB) material characteristics was studied, and a comprehensive index called solid filling rate was presented to describe the interaction of material characteristics, through analyzing the substance composition of CPB microstructure. Then, rheological experiments were made to get the corresponding rheological curves, which were fitted by the Bingham model to get the yield stress and plastic viscosity of CPB. The influence of material characteristics such as volume fraction, weighted average grain diameter, nonuniform coefficient, the mass fraction of fine particles and cement on CPB rheological parameters was analyzed, and its mechanism was explained from the view of microstructure. At last, a calculation model of rheological parameters including solid filling rate was constructed. The results indicate that under the same conditions, the yield stress and plastic viscosity increase exponentially along with the increase of volume fraction, decrease with the increase of nonuniform coefficient, and decrease first and increase soon with the increase of fine particles.