The influence of excessive oxide in cracking raw materials on the ethylene plant at a petrochemical company in Shandong is analyzed in detail. The excessive oxide in cracking raw materials produces methanol, organic acid, carbon monoxide, carbon dioxide and other oxides at high temperature in cracking furnace. These impurities seriously affect the stable operation of C₂ hydrogenation reactor, resulting in the low pH value of quench water and condensate between sections of cracking gas compressor, increased equipment corrosion and quench water emulsification, shorter service life of furnace tube, off-spec propylene product, increased grease production in caustic tower, poor adsorption capacity of molecular sieve of dryer and the pollution of pyrolysis gasoline, thus affecting the quality of C₄ and C₅ products.