Abstract: A dynamic model of deethanizer system has been developed by a process simulation software-HYSYS Dynamic based on a real specified LNG plant. Dynamic responses of process parameters such as temperature, pressure, product component, etc. have been studied when the factors such as reflux rate, reboiler heat load, etc. were changed. The measures have been taken to deal with the specified scenarios. The analysis showed that dynamic simulation could clearly reflect the dynamic response of the deethanizer system, predict the rationality of the system to deal with the interference factors, instruct the selection of equipment design margin during the design stage and verify the stability of the selected control system.