Abstract: Metal Zr tablet was used as quality control sample to monitor the long-term stability of L-edge densitometer, on which L-edge densitometer was used to measure the series of U reference solutions and Pu reference solutions in aqueous phase, and the U calibration curve and Pu calibration curve were drawn. The analytical methods for measuring U and Pu were established. The calibration curves were used to measure U and Pu reference solutions. The results show that the methods could measure both U and Pu in aqueous phase and organic phase. For the solution with U concentration above 10 g/L, the relative deviation of measurement results is less than 5%. For the solutions with Pu concentration above 5 g/L, the relative deviation of measurement results is less than 1.7%. It indicates that the method of measuring U and Pu with L-edge densitometer established in this paper has good accuracy and can be used for the measurement of U and Pu in practice.