The present invention provides an ethylene separation process comprising an first and second deethanizer columns and an acetylene converter, thereby providing an ethylene stream having a purity of 99 wt % or more to the middle of an ethylene separation column. The present invention increases the production amount of ethylene and also reduces energy consumption by passing the feed through a preliminary ethylene separation process, without having to change existing facilities in which an acetylene converter is provided downstream of the deethanizer column.