Objective: To prepare water-soluble chitosan(WSC) nanoparticles(WSC-NPs) and microspheres(WSC-MPs) , exam the morphology and particle sizes of them and study their effect on lowering lipids . Methods: WSC-NPs and WSC-MPs were prepared by ionic gelation process and spray-drying methods respectively. The effect of WSC-NPs and WSC-MPs on lowering lipids was evaluated by measuring its binding capacities of lipids in the conditions simulating human gastrointestinal tract in vitro. Also, the morphology and particle sizes of WSC-NPs and WSC-MPs were examined under scanning electron microscopy (SEM) and particle sizer. Resluts: WSC-NPs and WSC-MPs were nearly spherical in shape and the mean particles size varied from 200-400 nm and 3-7 μm respectively; The lipids-binding capacities of WSC-NPs and WSC-MPs were more effective compared with water-soluble chiosan. The lipids-binding capacity were enhenced when the particle size were decreased. Conclusion: WSC-NPs and WSC-MPs will be better fat-lowing food additives to replace water-soluble chitosan.