With the increase in the load of propylene rectification tower in a 220 kt/a ethylene plant, the propylene loss in the circulating propane at the bottom of tower reached 10％. In order to reduce the propylene loss at the bottom of propylene rectification tower, Aspen Plus was used to establish a propylene rectification tower model with the operation data of propylene rectification tower, and the current operation of the propylene rectification tower was analyzed and studied. By identifying the deviation points between the simulation data and the actual operating parameters, the operation of propylene rectification tower was adjusted and optimized, so as to reduce propylene loss at the bottom of tower, increase propylene production and achieve the purpose of improving quality and efficiency.