Abstract: Horizontal screen-bowl centrifuge works on the principle of separation by sedimentation. The better the effect of sedimentation separation, the higher the yield of dewatered product, and conversely, the lower the separating efficiency. With an aim to improve the separation efficiency and yield of dewatered product, a study is made on the screw parameters on fluid disturbance in screen-bowl centrifuge, so as to explore the law of the influence in the sedimentation-separation stage at different pitches, speeds and slip ratios of screw. Study results show the centrifuge′s separation efficiency is affected not only by size and density of feed material and also by degree of disturbance of fluid; and there are significant differences in influence between the operating parameters and structural parameters of the screw with the latter being a key influencing factor leading to disturbance of liquid. Based on these findings, work is made on structural optimization of the inner cylinder of the screw. The optimized screw′s material distribution structure shows a notably good effect in reduction of intensity of fluid disturbance. The study made herein may serve as a reference for optimum design of structural and operating parameters of the screw of screen-bowl centrifuge.