In order to study the flow field structure of HTPB propellant during the pouring process, the ameliorated Hurschel-Bulkley viscosity model, which can characterize the viscosity change of the solid propellant slurry during solidification, was used to simulate and analyze the pouring process of the slurry flooring. The theoretical results were compared with the experimental data, which show that the slurry will confluence after passing through the holes of the tube sheet. The slurry after confluence will accumulate in the engine shell under the action of gravity, while the surface of the slurry will be irregular concave and convex. However, under the action of gravity, the slurry will gradually be leveled and fill the holes without forming holes. A part of the strip separated by the tube sheet converges and flows downward along the groove between the wings, while the other part flows downward directly. During the flow process, the phenomenon of the tensile fracture occurs. The total pouring time is 104 min, the total mass of pouring slurry is 160.3 kg, and the average mass flow rate is 5.4 g·(hole·min)^-1. The error between the simulation value and the measured value is 8.65%, 2.06% and 5.93% respectively.