The industrial pseudo-boehmite was deeply characterized,and the impacts of pseudo-boehmite peptizing acid-to-alumina ratio,pseudo-boehmite content in the catalyst and alumina gel′s content on the cracking performance of heavy oil molecules of FCC catalysts were studied in detail.Results showed that when peptizing acid-to-alumina ratio（volume to massratio,mL/g） was increased from 0 to 0.20,pore volume of the catalyst was decreased from 0.39 cm³/g to 0.27 cm³/g.Acidity amount firstly increased and then decreased after acidification.Pore volume decreased and conversion ability of heavy oil firstly increased and then decreased.When pseudo-boehmite′s content in FCC catalyst was increased from 10% to 25%,conversion ability of heavy oil of the catalyst increased gradually,but with the increase of pseudo-boehmite content,the decreasing trend of heavy oil yield gradually decreased.The increase of alumina gel content would lead to a decrease in the pore volume of the catalyst and a decrease in the conversion capacity of the catalyst heavy oil.