Abstract: In order to ensure the smooth transportation of high concentration flling slurry and the effect of accumulation in goaf, this paper makes a preliminary stu dy of the effects of cement and fly ash as cementitious materials and aeolian sand as aggregates on the rheological properties of high concentration flling slurry under a series of samples with different gelling materials ratio. Test results show that, when the concentration and proportion of cemented material and aggregate are constan t, the shear stress, viscosity and thixotropy of the slurry decrease with the proportion of fly ash increases.When the concentration and the content of cement and fly ash in the cementitious material are constant, the shear stress, viscosity and thixotropy of the slurry decrease with the proportion of aggregate decreases.When the proporti on of cemented material and aggregate and the content of cement and fly ash in the cementitious material are constant, the shear stress, viscosity and thixotropy of the slurry decrease with the concentration of slurry decreases.Good fluidity and good thixotropy of the slurry material is conducive to slurry pumping. That is, the concentrati on of selected slurry and the proportion of cemented material and aggregate should be relatively small, and fly ash content in slurry should be relatively large .At this poi nt, shear stress and viscosity of the slurry are small. The fluidity of the slurry is better, and thixotropy of the slurry is poor.