Abstract: The content of mercury in Dictyophora was determined by automatic mercury analyzer and atomic fluorescence spectrometer. The main sources of uncertainty were analyzed and the main uncertainty components were calculated by establishing mathematical model, and the synthetic uncertainty and extended uncertainty were obtained, and the uncertainties results were compared. Results showed that, the expanded uncertainties of these two methods were 0.006 and 0.002 mg/kg(k=2), when the determination results of mercury were 0.050 mg/kg.This study might provide a guideline for uncertainty evaluation for determining mercury in edible fungus by automatic mercury analyzer and atomic fluorescence spectrometry.