Anionic polyacrylamide is a water-soluble linear polymer synthesized with a high degree of polymerization. It has valuable properties such as flocculation, thickening, shearing, resistance reduction, and dispersibility. Although the surface tension of anionic polyacrylamide decreases very little, but there are active groups in the molecule, which can change the interface state after being adsorbed on the interface. Its amide group (-CONH2) can form a hydrogen bond with many substances affinity and adsorption, which can make it bridge between the adsorbed particles, so that several or even dozens of particles are connected together, which can promote colloidal particles Aggregate into large flocs, accelerate the sedimentation of particles in the suspension, accelerate the clarification of the solution, and promote filtration.