PAPEMP is a new kind of water treatment agent. PAPEMP has high chelation and dispersion effects, high value of calcium tolerance, and good scale inhibition effects. PAPEMP can be used as scale and corrosion inhibitor in circulating cool water system and oilfield refill water system in situations of high hardness, high alkali and high pH value. PAPEMP has excellent scale inhibition ability to calcium carbonate, calcium sulfate and calcium phosphate. PAPEMP can efficiently inhibit the formation of silica scale, stabilize metal ions such as Zn, Mn and Fe. PAPEMP can be used as scale inhibitor for reverse osmosis system and multistep flash vaporization system in which high salt concentration, high turbidity and high temperature are usually encountered (such as high temperature and high turbidity in coal vaporization system), accessory agent for woven & dyeing (for example, yellow turnback inhibition agent), as alternatives of EDTA, DTPA and NTA.