Abstract: For tin, tungsten, titanium and other elements not easily digested by acid, a suitable sample preparation method combined with Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) can help to improve the accuracy and efficiency. Polymetallic ore samples were melted with Na₂O₂ and then extracted by mixed leaching solution (hydrochloric acid-tartaric acid-hydrogen peroxide).15 major and minor elements including Cu, Pb, Zn, Sn, W and Ti were determined by ICP-OES using an internal standard method. The analytical lines of analyzed elements and the correction mode of the background were optimized. The effect of crucible contamination, solvent, Al and internal standard element on the results were systematically studied. The method has detection limits of 7-995 μg/g, recoveries of 90.3%-105.0% (in Table 4), and relative standard deviations (RSD, n=12) of 0.8%-6.6% (in Table 3) by the standard addition method. For five different types of polymetallic ores, the method has a wide test range (40 μg/g to 25%).