Due to the need for better methods to upgrade heavy oil, selective ring opening (SRO) of multi-ring aromatics to mono-aromatics has attracted great interest. The SRO reaction can be done by hydrogenation and hydrocracking, catalyzed by the metallic (from metal element) and acidic (from zeolite) functions of bifunctional catalysts. We investigated the effect of wet-impregnated Ni and W metals over Beta zeolite on the characteristics of metal and acid sites, and found the correlation with their catalytic performance for the SRO reaction of 1-methylnaphthalene as a representative multi-ring aromatics. Primarily, W metal species was estimated to be more active than Ni metal species for the SRO reaction. Based on fundamental insight into these bifunctional catalysts, we described a facile approach to enhance the yield of the SRO reaction employing NiW-loaded Beta zeolite catalysts with various Ni contents. The balance of the metallic and acidic functions was modified by variation of the Ni content, and gradually shifted the product distribution showing a close relationship between the SRO performance and Ni content. We expect that this study can provide a logical perspective for designing selective bifunctional catalysts based on a better understanding of the interaction between metal and zeolite characteristics.