The polyaddition of bisphenol A diglycidyl ether with bis[4-(P,P-diphenylphosphinyloxy)phenyl] sulfone catalyzed by quaternary onium salt, such as tetrabutylammonium chloride afforded a new phosphorus-containing polyether with good solubility in common organic solvents. Having studied various factors affecting the reaction, such as temperature, catalyst concentration, reaction time, etc., an appropriate polyaddition condition was suggested as using 5 mol % of suitable quaternary ammonium or phosphonium salt in polar solvent at 150 degrees C within 25 h in an ampule for producing high molecular weight polymer. A number of polyethers bearing pendent phosphinate ester groups from the polyaddition of certain bis(epoxide)s and bis(phosphinate)s were synthesized under the above condition and characterized by GPC, IR, and NMR.