The effect of crystal size of USY zeolite on the performance of hydro-upgrading catalysts for treating catalytically cracked(FCC) LCO(light cycle oil) was studied.Three W-Ni catalysts supported on USY zeolites with different crystal sizes and Al2O3 were prepared by impregnation method.The catalysts were characterized by XRD and BET methods,and evaluated in a micro-reactor using tetralin as the model compound and in an 100-mL hydrogenation test unit using FCC LCO as the feedstock.By contrast,catalyst made from smaller crystal-size USY zeolite had higher external surface area and shorter pore length,having more hydrogenation activity sites and short contact time of reactant molecules with acidity sites.The evaluation results showed that the catalyst prepared on the basis of small crystal-size USY zeolite had higher tetralin conversion and better hydro-upgrading performance for treating FCC LCO. The effect of crystal size of USY zeolite on the performance of hydro-upgrading catalysts for treating catalytically cracked (FCC) LCO (light cycle oil) was studied. Three W-Ni catalysts supported on USY zeolites with different crystal sizes and Al2O3 were were prepared by impregnation method.The catalysts were characterized by XRD and BET methods, and evaluated in a micro-reactor using tetralin as the model compound and in an 100-mL hydrogenation test unit using FCC LCO as feedstock. By contrast, catalyst made from smaller crystal -size USY zeolite had higher external surface area and shorter pore length, having more hydrogenation activity sites and short contact time of reactant molecules with acidity sites. the evaluation results showed that the catalyst prepared on the basis of small crystal-size USY zeolite had higher tetralin conversion and better hydro-upgrading performance for treating FCC LCO.