The invention relates to a front-hydrogenation method of trace amount of acetylene in a methanol to olefin (MTO) apparatus. An adiabatic bed reactor for hydrogenation is located before a demethanizing column or a deethanizing column. A Pd-Cu-series catalyst is arranged in a fixed bed reactor. During preparation of the catalyst, a carrier is combined with a bipyridine derivative having a hydroxyl group, wherein a metal complex is formed from the hydroxylbipyridine derivative combined with the carrier and active components. Activity and selectivity of the hydrogenation method are greatly better than those in a conventional hydrogenation method, ethylene loss is reduced and hydrogenation activity is excellent, and outlet acetylene content is significantly reduced than that of another two hydrogenation methods. 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, so that the activity and the selectivity of the catalyst are maintained well, thereby prolonging the service life of the catalyst.