PESA is a multivariate scale and corrosion inhibitor with non-phosphor and non-nitrogen, it has good scale inhibition and dispersion for calcium carbonate, calcium sulfate, calcium fluoride and silica scale, with effects better than that of ordinary organophosphines. When built with organophosphates, the synergism effects are obvious. PESA has good biodegradation properties, it can be widely used in circulating cool water system in situation of high alkaline, high hardness and high pH value. PESA can be operated under high concentration index. PESA has good synergism with chlorine and other water treatment agents.