Abstract: A method of high resolution optical monochromatic system-continuum source atomic absorption spectrometry (HR-CS AAS) was proposed for the determination of lead (Pb) in gravity separation process samples of U-Nb-Pb polymetallic ore, with Pb 283.306 nm as the analytical line. The sample (0.030 0-0.200 0 g) was dissolved by a system of HCl (15 mL)-HNO₃ (5 mL)-HF (10 mL)-HClO₄ (2 mL) and dispersed in 10% (φ) HCl solution. As shown by the results, the detection limit (3s) was 0.021 mg·L^-1. Test for recovery was made by standard addition method for Pb in samples of U-Nb-Pb polymetallic ore, giving results in the range of 97.8%-103%, with RSDs (n=9) all less than 5.0%, and this results fulfiled the requirement of the national standard for geology and mineral industry (DZ/T 0130-2006).