Abstract: Y zeolites prepared by different modification methods were compared and characterized by N2 sorption isotherms, XRD, Py-IR, and TEM techniques. Catalysts of W-Ni supported on the modified Y zeolites with or without acid treatment were prepared by impregnation method, and the hydrocracking of vacuum gasoil (VGO) was performed on these catalysts. The results show that addition of acid treatment process after the Y zeolites modified procedure can increase the surface area, mesopore volume, and optimize acid sites of the modified Y zeolite. The catalyst using modified Y zeolites with acid treatment process exhibits better catalytic performance, higher yield and selectivity of middle distillates than the others.