The invention discloses a method for co-production of xylene and durene from C9+ heavy aromatic hydrocarbons. The method comprises that the C9+ heavy aromatic hydrocarbons are divided into C9-C10 heavy aromatic hydrocarbons and C11+ heavy aromatic hydrocarbons, the C9-C10 heavy aromatic hydrocarbons are converted into a primary mixed hydrocarbon product through catalytic cracking, the C11+ heavy aromatic hydrocarbons are converted into a secondary mixed hydrocarbon product through catalytic cracking, the primary mixed hydrocarbon product and the secondary mixed hydrocarbon product are mixed, dry gas, light hydrocarbons, benzene/toluene, xylene, trimethylbenzene and C10+ heavy aromatic hydrocarbons are separated from the primary mixed hydrocarbon product and the secondary mixed hydrocarbon product through multiple separation processes, the dry gas, light hydrocarbons and xylene as products are discharged, the benzene/toluene, trimethylbenzene and a certain amount of methanol undergo an alkylation reaction to produce a tertiary mixed hydrocarbon product rich in xylene and durene, the product without dry gas and waste water is returned and is further separated, the C10+ heavy aromatic hydrocarbons are subjected to crystallization separation so that durene and heavy component raffinate are obtained, the durene and a part of the heavy component raffinate as products are output and the rest of the heavy component raffinate is returned into a hydrocracking reactor. The method can produce xylene and durene having high additional values from the C9+ heavy aromatic hydrocarbons having low additional values as raw materials.