The invention relates to a selective hydrogenation method for a C2 fraction. In the method, a front hydrogenation process method with front deethanization is employed, wherein a material flow discharged from the top of a front deethanization column in an ethylene apparatus is fed into a fixed bed reactor to perform the selective hydrogenation. A Pd-Ag-series catalyst is arranged in an adiabatic bed reactor. During preparation of the catalyst, an 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. The method greatly improves the activity and selectivity of the hydrogenation reaction, reduces generation amount of green oil, prolongs service life of the catalyst, ensures qualified hydrogenation on the acetylene, and improves the stability of operation in an apparatus.