Chapter 6 provides a detailed introduction to natural polymer flocculants, successively elaborating on natural polymer substances such as starch, galactomannan, cellulose, chitin, lignin, tannin, microbial polysaccharides, animal gum, gelatin, and Moringa seed extract. For each substance, an overview is provided first, followed by an explanation of its structure and properties, and finally their applications in related fields, comprehensively demonstrating the characteristics and practical value of various natural polymer flocculants.