The invention belongs to the technical field of chemical preparations and relates to an ethylene glycol purifying process, comprising the steps of adding ethylene oxide and polyphosphoric acid into crude ethylene glycol, adding antioxidant, distilling under reduced pressure, and filling under nitrogen protection. The process of the invention can acquire ethylene glycol with very high purity and acidifying rarity, meets the application needs of precision electronics industry, and has better marketing competitiveness.