Abstract: To study the rheological properties of filling slurry, using the principle of hydrodynamics, a gravity flow test through a L-shaped pipe was carried out and the mechanical properties of slurry flow in the pipe was analyzed. The results indicated that the flow resistance and filling rate were depended on slurry concentration, flow rate and pipe diameter, among which slurry concentration was the predominant influencing factor. Under the condition of reasonable filling rates at which the gravity flow of slurry can be achieved, after determining the flow rate and pipe diameter based on filling ability, the slurry concentration can be adjusted in the filling station to obtain excellent results in transportation, sedimentation, anti-eduction, dehydration and drainage, concretion and mechanical properties.