Abstract: In this work, four types of screw elements were designed for the extrusion process of solid propellants, and the rheological properties of solid propellant slurry was investigated. Furthermore, the flow fields of the four screw elements were simulated by the Polyflow software. The shear rate, weight-average shear stress, mean reflux coefficient and cumulative residence time distribution were analyzed to characterize the mixing performance and flow field characteristics of screw elements. The dispersive and distributive mixing performance was comparatively investigated for these four screw element. The results indicated that the KB and SE elements had good comprehensive mixing performance, which favored the mixing process of solid propellants.