Purpose <p>This study aims to systematically evaluate the influence of screw design on axial particle mixing behavior in twin-screw systems, providing guidance for process optimization and rational screw geometry selection.</p> Methods <p>The Discrete Element Method (DEM) was employed to examine the influence of screw pitch and screw configuration on axial particle mixing. The mixing behavior along the screw axis was characterized through analyses of particle velocity distributions, residence time distributions (RTD), axial mixing indices, and particle trajectories.</p> Results <p>The results indicated that an excessively large screw pitch diminished both conveying efficiency and mixing performance. Screw pitch was found to modulate axial transport by affecting the stability of particle flow, which subsequently influenced axial mixing and the emergence of RTD tailing. Incorporating mixing elements enhanced mixing efficacy by amplifying fluctuations in particle velocity and facilitating randomized particle movement. Peaks in contact force, kinetic energy, and granular temperature were detected within the regions containing mixing elements.</p> Conclusion <p>For high-throughput conditions, conveying elements are preferred to ensure transport stability. For high-homogeneity systems, kneading elements enhance mixing, while toothed mixing elements serve as auxiliary components for local mixing. Therefore, screw design should balance mixing intensity and conveying capacity based on process requirements.</p> Graphical Abstract <p></p>