The invention relates to a heavy aromatics light catalyst for high-yield production of xylene and preparation method of catalyst, and mainly aims to solve the problems of low heavy conversion level of heavy aromatics, low yield and selectivity of xylene and high deactivation rate of catalyst in the prior art. The problems can be solved by adopting a technical scheme that the catalyst is prepared from the following components in percentage by weight: 30-60 percent of a mixture of MFI-type zeolite and ZSM-12 molecular sieve, 38.5-69.8 percent of at least one of gamma-alumina, eta-alumina and pseudo-boehmite serving as adhesive, 0.1-0.5 part of at least one metal of Pt, Pd and Ir and 0.1-1 percent of at least one metal of Zn, La, Ce and Bi. The catalyst can be used in industrial production for converting heavy polycyclic aromatic hydrocarbon into mononuclear aromatics to increase yield of xylene.