The invention relates to a method for preparing 2, 2'-dimethyl-1, 1'-dianthraquinone from 1-chlorine-2-methylanthraquinone, which comprises dissolving 1-chlorine-2-methylanthraquinone in aprotic organic solvent 1, 3-dimethyl-2-imidazolone, stirring and reacting for 9-11h at 180-200DEG C in the presence of copper powder catalyst, cooling to room temperature, filtering the precipitated deposits to attain crude product of 2, 2'-dimethyl-1, 1'-dianthraquinone, washing crude product via clean water, arranging washed crude product into a hydrochloric acid solution containing dissolved sodium chlorate, raising temperature to 70-90DEG C, stirring for 2h, removing copper, filtering, washing filter cake with water till to neutral and drying to obtain 2, 2'-dimethyl-1, 1'-dianthraquinone. The fusionpoint of the inventive product is 330-332DEG C and the product yield is 82-84%.