The invention belongs to the technical field of synthesis of organic functional materials intermediates, relating to the synthetic method of 6, 11-dichloro-5, 12-naphthacenequinone. The method comprises the following steps: 2-((1-hydroxy-2-naphthyl)carbonyl) benzylacid and PCl5 are mixed for chlorination reaction and cyclization reaction; after the reactions, through the process of cooling, filtering, washing and drying reactants at room temperature, an intermediate product is got; then the intermediate product and concentrated sulphuric acid are mixed, react, are cooled and then poured into ice water, after the process of filtering, washing, drying, 6, 11-dichloro-5, 12-naphthacenequinone is produced. The 6, 11-dichloro-5, 12-naphthacenequinone can be purified by xylene recrystal. The synthetic method features simple process and easy operation, and takes the 2-((1-hydroxy-2-naphthyl)carbonyl) benzylacid as the raw material to realize simultaneous reactions of chlorination and cyclization under low temperature and without solvent. The addition of the concentrated sulphuric acid realizes complete cyclization reaction and relatively single products which are easy to separate and purify and have high productivity.