Abstract: Taking the No.2 gas fractionation unit with the capacity of 0.48 Mt/a of SINOPEC Yangzi Petrochemical Co. Ltd. as the research object，the Aspen Plus process simulation software was used to establish steady-state model of the gas fractionation unit. The simulation results were consistent with the actual production of the unit. Based on the above results，the sensitivity analysis tool was used to optimize the analysis of important operating parameters such as the top pressure and reflux ratio of the distillation column of the unit，with the goal of reducing energy consumption and maximizing propylene production，while ensuring the quality requirements of each product. The optimization results proved that under increasing the pressure at the top of the propylene rectification column and the propylene product quality，the propylene yield of the gas fractionation unit was improved. After optimization，the yield of propylene product increased by 0.08 percentage point，and the annual economic benefit was about 920 500 Yuan. The application of process simulation to optimize the production of propylene has a significant effect.

Key words: process simulation, gas fractionation column, propylene, sensitivity, rectification column