Ethylene and propylene are the main basic products of petrochemical industry and dominate the petrochemical industry. Ethylene yield and ethylene and propylene yields are important economic and technical indicators of ethylene plant. The cost of ethylene raw materials accounts for more than 70％ of the production cost. Improving the ethylene and propylene yields of the plant and reducing the raw material consumption per unit product can greatly reduce the cost per unit product, thereby enhancing the competitiveness of the enterprise. The ethylene yield and the ethylene and propylene yields can be effectively improved by means of using light raw materials, optimizing the operation of cracking furnace and quenching system and adopting CCC control for compression system, and the processing energy consumption of the plant can be greatly reduced. While improving the ethylene yield, the plant encountered some problems such as low quench oil temperature and excessive fuel gas output, which became the bottleneck restricting the further reduction of energy consumption. How to effectively solve the bottleneck problem becomes the key direction of the next step.