The invention discloses citrate ether polymeric polylol and a preparation method and application thereof. The method comprises the first step of an esterification reaction of citric acid, wherein citric acid, micromolecular polylol, an esterification catalyst and an antioxidant are taken for the esterification reaction which is over when the acid value is smaller than 1.5 mg/g, unreacted micromolecular polylol is removed in vacuum, and then citric acid polyol ester is obtained; the second step of an etherification reaction of the citric acid polyol ester, wherein the citric acid polyol ester, an etherification catalyst and epoxypropane are subjected to the etherification reaction, and after the reaction proceeds to be under negative pressure, vacuum is pumped, the product is taken out under nitrogen protection, the obtained product is neutralized until the pH is 7, kieselguhr is added, and suction filtration is performed to obtain the final product. The prepared polylol is light-yellow transparent liquid with the viscosity range of 1000-7500 mPa.s, the hydroxyl value range of 250-600 mg/g and the acid value smaller than 1.0 mg/g. The raw materials in use are wide in source and reproducible, and therefore rigid polyurethane foam made from the polylol is good in degradability.