Abstract: The authors develope an expert control system by applying intelligence control principle,advanced control principle and the craft operation experience.This expert control system is based on the normal regulations control project and the soft-sensing model of product composition.According to the experience of experts,this expert control system intermittently regulates the set points of reflux ratio and sensitive plate temperature so as to reduce energy consumption and raise ethylene collection efficiency.The system must work under the premise that guarantees the product quantity near to the qualified line possibly,and makes operation control on the level of quantity qualified.Thus,the expert control system can decrease reflux ratio(increasing yield)and reduce heat consumption of reboiler(reducing energy consumption).By combining the real-time communication ability,exploitation condition of DCS and the principle of expert system,and making use of the soft and hardware resources of system,we have developed a real-time and open expert control system that is based on the experience knowledge,the craft mechanism.(Anticipant) economy energy object is obtained through the engineering implement.