This study analyzes the causes of leakage in the convection section coils of cracking furnaces in domestic ethylene plants. It is concluded that combined factors including thermal stress, internal medium effects, high-temperature oxidation corrosion, and flue gas dew point corrosion are the primary causes of the perforation leakage and cracking in convection section coils. Preventive measures to mitigate coil corrosion are also proposed.