Inspection of long-term operating atmospheric and vacuum distillation units reveals that non-uniform thinning frequently occurs in the outlet pipeline of the atmospheric tower overhead air cooler, with local thinning rates exceeding 30%. The risk of pipeline perforation and rupture increased significantly, which could easily cause overhead oil and gas leakage. Analyses were carried out from some dimensions including pipeline material, operating condition and process anticorrosion technology. The results show that pipeline wall thinning primarily originates from erosion corrosion induced by gas-liquid two-phase flow, as well as under-deposit corrosion resulting from ammonium salt crystal deposition in the low-temperature zone at the atmospheric tower overhead. In response to this problem, a series of anti-corrosion optimization plans were proposed, including improving pipeline materials, introducing ultrasonic-electric desalination synergistic demulsification technology, strengthening crude oil demulsification to reduce the amount of chloride ions carried, expanding overhead water injection volume, and adding online desalination facilities. Relevant measures can effectively mitigate the corrosion rate of the tower overhead system, extend the service life of the equipment, and provide technical support for the safe, stable, and long-term operation of atmospheric and vacuum distillation unit.