The invention provides a method for measuring content of phenolic hydroxyl groups in polyphenyl ether by titrimetry. The method comprises the following steps: dissolving polyphenyl ether to be measured in an organic solvent, adding a reagent, and heating at 0-60 DEG C for 10-30 minutes; and cooling to room temperature, adding de-ionized water, dropwisely adding several drops of phenolphthalein indicator solution, titrating by using a standard potassium hydroxide water solution until pink stays fadeless for 30 seconds, and calculating the content of phenolic hydroxyl groups in polyphenyl etheraccording to the blank experiment. The method has the advantages of simple experimental apparatus and high measuring accuracy.