The invention belongs to the technical field of organic compound syntheses, and provides a preparing method of a 9,10-phenanthraquinone compound. The preparing method aims at solving the problems that as for methods for synthesizing 9,10-phenanthraquinone compounds at present, the price of an oxidizing agent is high, the environment is polluted, operation is complex, the number of by-products is large, cost is high, the yield is low, and raw materials are not easy to obtain. The preparing method includes the steps that substituted methylphenylacetic chalcone serves as a starting material, copper powder serves as a catalyst, 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octanebis(tetrafluoroborate) serves as an oxidizing agent, the mixture is reacted in a solvent for 12 hours to 24 hours at the temperature of 25 DEG C to 80 DEG C, and the 9,10-phenanthraquinone compound is obtained. The defects in the prior art are overcome through the preparing method, and the synthesizing method has the advantages that the catalyst is low in price and easy to obtain, toxicity is small, an oxygen source is easy to obtain, the environment-friendly effect is achieved, the reaction condition is mild, functional-group universality is good, and operation is easy and convenient.