Water treatment agent is a necessary chemical agent in the process of industrial water, domestic water and waste water disposal. Its primary effect is to control the formation of scale and sludge, reduce foam, reduce data erosion in contact with water, remove suspended solids and toxic substances in water, deodorize and decolorize, soften water quality, etc. At present, because of the rapid increase of water consumption in countries around the world, various environmental protection laws (water purification laws) have been formulated one after another, and the requirements are increasingly stringent, so the efficient water treatment agents are rapidly increasing. In China, the contradiction with the increasingly serious water capital crisis is that the production capacity of water treatment agents is very low, the quality is not guaranteed, so accelerate the development of China's water treatment agents this environmental information property fire.Water treatment agents flocculant, corrosion inhibitor, scale inhibitor, algae killer, defoaming agent, cleaning agent, dehydrating agent, decolorizing agent, dephosphorization agent and ion exchange resin. Flocculants and biocides are systematically introduced in this paper.China's water treatment agent is in the 1970s after the introduction of large chemical fertilizer plant to cause attention and gradually developed; Since then, a series of water treatment agents have been developed by ourselves. The varieties of water treatment agent in China mainly include scale inhibitor, corrosion inhibitor, germicidal and algicidal agent, defoaming agent, organic flocculant and so on.