Abstract: A method for the determination of trace mercury in barite ores by atomic fluorescence spectrometry with sulfhydryl cotton separation and enrichment was reported. The sample was treated with EDTANaOH after sample grinding and screening. Trace mercury in the sample was released from HgEDTA complex by adjusting the sample solution to weak acidity with HCl. At pH 3~4, sulfhydryl cotton was used to absorb the mercury and organic and inorganic mercury were eluted by 2 mol/L and 6 mol/L of HCl respectively. After transferring organic mercury into inorganic mercury, total mercury was determined by AFS. The detection linear rang of the method was 0.00~5.00 ng/mL for Hg (R2 =0.9996). The recovery ranged from 92.0% to 114.0%. The experimental condition was optimized and the factors influencing the determination of Hg were discussed. The method provides the advantages of high sensitivity, less interference, simple operation and high efficiency.