Abstract: The sample was digested using the semi-melting method with Aiskaer reagents (sodium carbonate and zinc oxide) and extracted by boiling water which separated Selenium from the main metal elements including Cu, Pb, Zn, other transition metals and precious metals. Meanwhile, other interference elements remaining in the solution are sheltered by adding molisite. A method for determining trace Selenium in copper ore, lead ore and zinc ore by hydride generation-atomic fluorescence spectrometry has the advantages of low interference and high sensitivity. The best measurement conditions are 30% for hydrochloric solution, 20 g/L for KBH₄, 1 mg/mL for molisite and permissible dosage of interference elements: Cu 40 mg/L, Pb 8 mg/L, Zn 400 mg/L. In addition, separation efficiency experiments were conducted for primary elements including Cu, Pb, and Zn. The detection limit of the method is 0.0203 μg/g for Se and measuring range of the method is 0.15~100 μg/g. This method was used to conduct experiments in seven labs from different areas using national standard materials with a precision repeatability limit, good reproducibility limit and high accuracy. The method discussed in this paper can be applied to determine trace Se in soil and multimetallic minerals.