The characteristics of spray - dried polyaluminium chloride (PAC) depend on the operation principle of the pressure spray. The spray polyaluminium chloride is atomized into small particles when it is dried. This particle form has good application performance. Polyaluminium chloride is water soluble material, has good thermal stability and high solubility, in the process of drying, the 40-50% of aluminium chloride solution into a high pressure pump, through the pressure into the atomizer in the dryer after atomization, dispersed into tiny droplets, droplets are granular products after drying, drying and granulating completed at the same time.