Abstract: In order to accurately determine the molybdenum content in the tungsten-containing cobalt-molybdenum catalyst, the lead molybdate gravimetric method was adopted to determine the major molybdenum, while inductively coupled plasma atomic emission spectrometry (ICP-AES) was adopted to correct and determine the residual molybdenum. The total molybdenum content in the sample was calculated as the sum of these two determination. The sample was digested with the four acid mixture (hydrochloric acid, hydrofluoric acid, nitric acid, and perchloric acid), followed by repeated filtration, washing, and the solution acidity adjustment to achieve the separation of impurities from molybdenum. In the processed solution, 15 mL of 50 g · L⁻¹ ethylene diamine tetraacetic acid solution was added, and after adjusting the solution acidity, 50 mL of acetic acid-ammonium acetate buffer solution was added. The mixed solution was heated, and 20 g · L⁻¹ lead acetate solution was added dropwise under boiling condition until the precipitation appeared. Then, 50 mL of 20 g · L⁻¹ lead acetate solution was added at a rate of 3-5 drops per second, and the boiling state was maintained for 15 min. The solution was settled for precipitation at 70 ℃ for 40 min, which was then filtered. The filter paper and precipitate were placed in a porcelain crucible, dried and ashed, then ignited at 550 ℃ to a constant weight. After cooling, the mass was weighed, and the mass fraction of major molybdenum was calculated. For the molybdenum lost during separation, the residue and filter paper containing molybdenum were mixed with 4.0 g of the mixed flux (a mixture of anhydrous sodium carbonate and zinc oxide at a mass ratio of 2∶1), covered with 2.0 g of the mixed flux. The mixture was sintered at 700 ℃ for 40 min, leached with hot water, and diluted to 250 mL with water after cooling, then filtered. A 20 mL aliquot of the filtrate was transferred to a 100 mL-volumetric flask, 10 mL of hydrochloric acid was added. The solution was diluted to the volume with water, and the mass fraction of residual molybdenum was determined by ICP-AES at the analytical wavelength of 202.030 nm. As shown by the results, linear relationship between values of the mass concentration and spectral line intensity of molybdenum was kept in the range of 30 mg · L⁻¹ for ICP-AES, with a detection limit (3s) of 0.001 5%. RSDs of 11 repeated determinations of the actual sample was 0.20%, and the recovery of molybdenum obtained by the standard addition method in the range of 98.6%-99.6%. This method was applied to analysis of two molybdenum concentrate standard materials with added tungsten, and absolute values of the determined values were less than 0.20%.