Polyaluminum chloride is a new type of inorganic polymer water purification flocculant. It is a hydrolysis product between aluminum trichloride and aluminum hydroxide. It has strong bridging adsorption performance and is easily soluble in water. The hydrolysis process is accompanied by electrochemical condensation, adsorption and precipitation and other physical and chemical processes, which can remove toxic substances and heavy metal ions in the water. The water purification effect is far superior to traditional low-molecular-weight water purifiers such as aluminum sulfide, ferric chloride, iron sulfate and alum.