Abstract: The final operation temperature of heat exchanger of Dushanzi Petrochemical Refinery distillation unit was about 275 ℃, which was 25 ℃ lower than design value of 300 ℃. It resulted in high load operation of the atmospheric furnace. When the processing quantity was increased to 1 010 t/h, the furnace temperature was close to 900 ℃, Which was the upper limit of process index. In order to alleviate the long-term high load operation of atmospheric furnace, the side stream extraction pipeline was added on the initial distillation tower, which made it possible that part heavy naphtha entered atmospheric distillation tower via return pipe of the first medium without being heated in atmospheric heating furnace. The atmospheric furnace load was reduced by 3.46%, the processing capacity of the unit was improved by 41 t/h, and the fuel gas consumption of the furnace was reduced by 2 937 t/a, which improved the operation efficiency of the unit.