The invention relates to a high-performance polycarboxylate based polyether water reducing agent, which is characterized by comprising the following components in percentage by weight: 13 to 16 percent of polyethylene glycol monomethyl ether, 5 to 8 percent of methacrylic acid, 0.6 to 0.9 percent of ammonium persulphate, 0.4 to 0.8 percent of sulfuric acid, 6 to 7 percent of ionic membrane alkali and 65 to 75 percent of deionized water. The polyethylene glycol monomethyl ether and the methacrylic acid are esterified at the temperature of 100 to 130 DEG C in the presence of a specific catalyst, namely the ammonium persulphate and then subjected to oxidation polymerization at the temperature of 80 to 90 DEG C in the presence of a specific oxidant, namely the sulfuric acid, to form a synthetic product of a specific structure. After a synthetic process is completed, the pH value of the synthetic product is adjusted at a normal temperature and the final product is formed. Apart from relatively high stability, the water reducing agent has the characteristics of low admixture, high water reducing rate, wide cement adaptability, high slump retaining capacity, good dispersion effect, high environmental friendliness, and the like when applied to concrete.