Anionic polyacrylamide (APAM) is composed of copolymerization of acrylamide and acrylic acid salt, is a water-soluble, linear polymer flocculant, by neutralizing the charge on the surface of the suspended particles in water to promote flocculation particles, particles so that the water stability, stability after off particles in polymer active gene bridge under the action of mutual adsorption and eventually form a larger floccules.