Abstract: Zeolite Y/mesoporous Al-SBA-15 composite with highly hydrothermal stability and dealuminated Y zeolite with mesopores were prepared by a two-step method and an acid - hydrothermal treatment integrated method respectively. Their catalysts were prepared by an impregnation method using as-prepared materials. By using XRD，N2 sorption isotherms，SEM，XRF，and TEM techniques，comparative analysis was carried out between the zeolite materials and their catalysts. The mesopore size distribution of Zeolite Y/mesoporous Al-SBA-15 composite was from 7 to 10nm，which was larger than that of dealuminated Y zeolite，from 3.5 to 4.5nm. Zeolite Y/mesoporous Al-SBA-15 composite as catalyst support played an important role in providing acid sites，increasing pore volume and average pore diameter. The catalytic performance of the two catalysts for hydrocracking heavy oil was evaluated under the same condition. Experimental results showed that the catalyst containing zeolite Y/mesoporous Al-SBA-15 composite resulted in 66.21% of middle distillates yield，5.68% higher than that of dealuminated Y zeolite. The middle distillates selectivity was 84.5%，5.7% higher than that of catalyst containing dealuminated Y zeolite.