This paper focuses on the bottlenecks in the long-term operation of cracking furnace in the 1000 kt/a ethylene plant at PetroChina Dushanzi Petrochemical Company, analyzes the causes of the problems, and takes reasonable measures to solve the problems including the frequent leakage of primary steam injection line, the blockage of furnace tube in the radiant section of cracking furnace, the leakage of furnace tube in convection section, the leakage of boiler feed water regulating valve, the leakage of steam drum connecting elbow, the vibration shift of zirconia and the blockage of light hydrocarbon regulating valve cage. The operating cycle of cracking furnace was improved, and the economic benefit of the enterprise was increased.