The invention relates to a method of purifying ethylene through selective hydrogenation. An adiabatic bed reactor for hydrogenation is arranged after an ethylene rectification column and before an ethylene polymerization reactor. A Pd-Ni-series catalyst is arranged in a fixed bed reactor and is prepared with an alumina-series carrier. During preparation of the catalyst, the alumina-series carrier is combined with a bipyridine derivative having a hydroxyl group, wherein a metal complex is formed from the hydroxyl bipyridine derivative combined on the carrier and an active component. With the catalyst, activity and selectivity of the hydrogenation method are greatly better than that in a conventional hydrogenation method, and purity of ethylene is increased so that performance of a polymerization-grade ethylene product is improved well. Through reduction on green oil, active center of the catalyst is not covered by side product, thereby prolonging the service life of the catalyst. The catalyst has excellent anti-impurity-interference capability and is suitable for an ethylene selective hydrogenation device being high in content of impurities, such as sulfur, arsenic and the like.