An optimized diesel hydrocracking catalyst and a method for preparing same. Raw materials comprise the following components in percentage by weight: 1-25% of modified molecular sieve, 10-65% of γ-Al2O3, 15-70% of amorphous silica-alumina, 9-40% of binder, and 10-35% of active metal oxide. The specific surface area of the catalyst is 200-450 m2/g, and the total pore volume is 0.30-0.65 cm3/g. To obtain a carrier, a modified molecular sieve is added to an inorganic aluminum salt solution used for preparing γ-Al2O3, and precipitation, drying, and roasting are performed to obtain a composite of molecular sieve and γ-Al2O3; then the remaining materials are mixed with the composite according to the material proportion of the catalyst, and rolling, forming, drying, and activation are performed to obtain the catalyst. The molecular sieve in the catalyst carrier has a high silica/alumina ratio and high specific surface area, and is highly dispersed in the carrier; thus, the carrier has more uniform acid sites, and alumina is in closer contact with the molecular sieve; and therefore, the catalyst can remarkably reduce the pour point of a diesel fraction and improve the cetane number of diesel while guaranteeing a high diesel yield.