A method for indirectly determining the molybdenum in Chinese herbal medicine by butanol extraction and dilute hydrochloric acid dissolution was established for atomic fluorescence spectrometry. The molybdoarsenate heteropoly acid, formed in the presence of As(Ⅴ) and ammonium molybdate in 0.3 mol·L-1 sulphuric acid medium, was separated and enriched in the organic solvent, then the evaporation of organic reagent was implemented and the left residue was dissolved in dilute hydrochloric acid in which the arsenic content was determined on behalf of molybdenum. In the optimum experimental conditions, molybdenum content in 0～15 μg·L-1 range depicts a good linear relationship, the detection limit and relative standard deviation of 0.44 μg·L-1 and 1.1% were obtained, respectively. Spiked Chinese herbal medicine samples were determined with the proposed method, and recoveries of 95.6%～101.3% were achieved.