In this article ,we used GC-MS to confirm the structure and content of the impurities in fluorene. The material balance of each component of reactants and products reveals that in the preparation of fluorenone from the oxidation of solid fluorene reaction with xylene used NaOH as catalyst and quaternary ammonium salt as the phase transfer agent and air as oxidant, conversion yield of fluorene is 100%,product yield of fluorenone and water is 100% with no other by-products, meanwhile, there was no change in the number of the impurities in fluorene during the reaction, the moles of each component also remained the same. The result was verified by the reaction of pure fluorenone from the oxidation reaction of pure fluorene in the same condition. After fluorenone was isolated from the reaction, solvents, catalysts, phase transfer reagent can be recycled. The reaction mechanism was also discussed.