Abstract: Both an absolute measurement technique and a relative measurement technique are proposed for the determination of 241Am in plutonium by NaI (T1) γ-spectrometry. Seven standard solutions with different ratios of 241Am and Pu are prepared and used for the calibration. When the ratios of the disintegration rate of 241Am and Pu are within the range from 5×10-4 to 1.6,the accuracy of the methods is≤±1%.