A method for preparing di-2-ethyhexyl carbonate is disclosed and is a method which employs a choline chloride functional ionic liquid as a catalyst, employs dimethyl carbonate and isooctyl alcohol as raw materials and employs two steps of transesterification for preparing di-2-ethyhexyl carbonate. The method comprises: firstly adding isooctyl alcohol and the choline chloride functional ionic liquid into a reactor, stirring to raise the temperature to 60-100 DEG C, then slowly dropwise adding dimethyl carbonate, after dripping is finished, keeping warm for reacting for 0.5-4.0 h, then raising the temperature to 80-150 DEG C and reacting for 2-8 h, and then performing reduced-pressure distillation to obtain di-2-ethyhexyl carbonate. By adjusting the proportions of dimethyl carbonate, isooctyl alcohol and the choline chloride functional ionic liquid, the kinds of the ionic liquid, the reaction temperature and the reaction time, di-2-ethyhexyl carbonate with relatively high purity is obtained, and the yield of di-2-ethyhexyl carbonate is better than that of di-2-ethyhexyl carbonate prepared by employing a conventional solid alkali catalyst. By employing the choline chloride functional ionic liquid as the catalyst, the choline chloride functional ionic liquid is high in catalytic activity, free of toxicity, easily degradable, easily separable and reusable, so that the preparation cost is reduced and pollution to environment is reduced.