Abstract: During solid propellant production, multi-component particles and binders need to be stirred in a mixing kettle to form a slurry and then pressure-poured into the motor chamber. The complex interfacial dynamics of multiphase components during mixing, along with the high yield stress and the discontinuous extrusion of slurry during casting are difficult to be effectively simulated by means of traditional grid-based methods. Based on the smoothed particle hydro-dynamics (SPH) method, combined with the Herschel-Bulkley-Papanastasiou constitutive model and the multi-component description framework, a numerical model suitable for the mixing and casting processes of solid propellant slurry was established, and the mixing experiment was carried out. The results show that this method has high accuracy while simulating Newtonian and non-Newtonian fluids. The simulation deviations of N_p-Re power characteristic curves of Newtonian and non-Newtonian fluids are 7.6% and 1.7%, respectively. SPH simulations of planetary mixing reveal chaotic effect from stirring and kneading of solid and hollow double blades, as well as the synergistic effect of high-vorticity hot spots. After mixing, the slurry reaches a uniform state with a density difference within ≤80 kg/m³, and the uniformity square deviation tends to be stabilize after four evolutionary stages. The shear-thinning of the mixture promotes the formation of spiral band of high-vorticity hot spots near hollow blades. For vacuum casting, the SPH simulation completely captures the extrusion-fracture-retraction, leveling accumulation and wetting penetration behavior of the slurry, and verifies dislocation arrangement effectiveness of the core mold and the pouring hole, indicating that the liquid level is highly consistent in the area away from the injection hole, and the slurry has good leveling.