A　series　of　Zr　incorporated　small　crystal　size　Y　zeolites　were　successfully　synthesized　by　a　direct　hydrothermal　method,　and　the　corresponding　NiW　catalysts　were　prepared　for　the　hydrocracking　of　vacuum　gas　oil　(VGO).　The　synthesized　zeolites　and　prepared　catalysts　were　characterized　by　XRD,　SEM,　FTIR,　Pyridine　FTIR,　H-2-TPR　and　TEM　techniques.　The　results　show　that　the　synthesized　zeolites　have　uniform　morphology　and　small　crystal　size,　while　Zr4+　incorporated　into　the　framework　of　Y　zeolite　has　been　confirmed　by　XRD　and　FTIR.　The　amount　of　acid　sites　of　xZrY　zeolite　slightly　increases　compared　with　that　of　Y　zeolite　by　Pyridine　FTIR.　Moreover,　the　Zr4+　incorporation　into　Y　zeolite　can　increase　the　W　species　reducibility,　modulate　the　length　and　stacking　of　WS2　phase,　and　enhance　the　W　species　dispersion　on　the　catalyst　surface　by　H-2-TPR　and　TEM,　which　favor　to　improve　the　hydrogenation　activity　of　the　catalyst　to　tune　the　balance　between　cracking　activity　and　hydrogenation/dehydrogenation　activity.　Hence,　the　catalyst　containing　xZrY　zeolite　exhibits　not　only　higher　yield　and　selectivity　of　middle　distillate　but　also　slightly　higher　conversion　of　VGO　compared　with　the　catalyst　containing　Y　zeolite.