To　deeply　illuminate　the　effect　of　ASA　composition　on　its　corresponding　Mo　catalyst　properties　and　performance　for　the　slurry-phase　hydrocracking　of　vacuum　residue,　the　amorphous　silica-alumina　(ASA)　samples　with　the　various　ratios　of　Al　to　Si　were　successfully　synthesized　by　a　simple　co-precipitation　method,　which　have　the　different　acid　properties　and　pore　structure,　especially　ASA-1　with　lowest　ratio　of　Al　to　Si　owning　the　largest　number　of　B　acid　sites　and　the　highest　volume　of　mesoporous.　Additionally,　the　Mo　catalyst　supported　on　ASA-4　possesses　the　highest　dispersion　of　MoS2　slabs　and　largest　amount　of　Mo　atoms　located　at　the　edge　sites　among　all　the　catalyst,　possibly　due　to　the　appropriate　surface　properties　of　ASA-4　derived　from　the　ratio　of　Al　to　Si,　it　demonstrates　that　the　most　exposure　Mo　active　sites　are　present　on　Mo/ASA-4　catalyst.　The　hydrocracking　evaluation　results　show　that　the　VR　conversion　over　the　different　catalysts　are　similar,　it　may　be　ascribed　to　the　variation　of　acid　properties　and　pore　structure　insufficient　to　change　VR　cracking　pathway　because　of　the　low　catalyst　dosage.　Furthermore,　the　Mo/ASA-4　catalyst　exhibits　the　higher　yield　of　naphtha　and　middle　distillate　and　inversely　the　lower　yield　of　gas　and　coke　in　comparison　with　other　catalysts,　it　should　be　attributed　that　the　higher　hydrogenation　activity　derived　from　the　more　exposure　Mo　active　sites　can　efficiently　restrain　the　over　cracking　of　the　intermediate　product　and　aggregation　of　the　polycyclic　aromatic　hydrocarbon　in　the　hydro　cracking　process.