Abstract: Abstract: The heat integrated distillation column (HIDiC) is a new type of efficient distillation unit. In this paper, the performance of HIDIC on separation of complex C5 fraction, which is byproduct of oil cracking during producing ethylene, is investigated with chemical engineering simulation software ASPEN PLUS. The HIDiC and conventional column(CDiC) have similar product composition under the same operating condition, which proves that HIDiC is feasible in separation of C5 mixture. The effects of compression ratio and heat duty distribution model on the energy consumption are studied, and the tower structure is optimized. The optimized internal heat integrated distillation column provides energy saving effect of 86.7%, and the total annual cost reduced by 7.4% compared to the conventional distillation column.