The amount of ethylene in refinery off-gas is high with a mass fraction of 20%, but the refinery off-gas is usually used as fuel gas in most refineries. The separation and recovery of ethylene is of remarkable significance for saving energy and reducing carbon dioxide emission. The aim of this paper is to use a novel absorbent mesitylene for the ethylene absorption process and assess its application feasibility through the ethylene + mesitylene vapor-liquid equilibrium data measurement and its binary interaction parameter correlation, as well as the simulation for ethylene separation process.