Abstract:The paper describes the evaluation on the uncertainty of the arsenic measurement in geochemical samples by hydride generation-atomic fluorescence spectrometry. The resources and types of the uncertainty are summarized. The effect to arsenic measurement in geochemical samples is analyzed and presented. By the evaluation on the uncertainty of the arsenic measurement, the uncertainty mainly comes from the sample making, standard curve fit by least squares method, standard stock solution adjusted and diluted, and the repeated times. The evaluation indicated that the uncertainty from the standard stock solution adjusted and diluted is the most important factor to the uncertainty, and the standard curve fit by least squares method is the second source of uncertainty.