This study integrates numerical simulations and tribological experiments using a plate-on-disc tribometer to examine the tribological behavior and wear mechanisms of cellulose materials in the solid transport screw of a parallel co-rotating twin-screw extruder. EDEM simulation results indicate that wear on the left screw primarily occurs on the screw threads while wear on the right screw is concentrated at the junction between the screw threads and the bottom of the screw groove. The meshing region experiences the most severe wear due to the combined effects of shear forces and contact stress. Tribological experiments with a plate-on-disc tribometer reveal that adding cellulose with higher aspect ratios reduces friction coefficients. When cellulose has a high aspect ratio, it improves the alignment of wear scar cracks and cellulose molecular chains on the friction contact surface. This results in a gradual alignment of rod-shaped structural cellulose in the direction of frictional sliding, which reduces impact-spalling wear, micro-cutting wear, and scratching abrasion wear. Additionally, cellulose with higher aspect ratios can withstand higher rotational friction speeds during high-speed friction, forming an orientation transfer layer on the friction contact surface. This enhances surface lubrication and reduces abrasive wear and adhesive wear.