Abstract: Cr, As, Cd, Hg and Pb in iron ores not only contaminate smelting facilities and affect the quality of final products, but also pollute the environment. Cr, As, Cd, Hg and Pb contents in five certified standard iron ore samples of BS105, JSS804-2, Euro680-1, JK42 and ASCM007 were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) with microwave. Compared with the routine methods of Atomic Absorption Spectrometric (AAS) and Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), this method has the advantages of using a small sample weight of about (0.1000±0.0200) g, needing less acids for digestion as 2.5 mL HCl+0.5 mL HF+1.0 mL HNO₃, less effluent and has a lower cost. There are small interferences without preparation of the Fe base solution and any addition of masking reagent. Results for Cr, As, Cd, Hg and Pb in the Fe ore samples are 5.5×10^-10-2.5×10^-4, 7.6×10^-10-1.9×10^-4, 4.5×10^-11-5.5×10^-6, 1.88×10^-9-1.9×10^-7 and 1.2×10^-10-3.2×10^-5, respectively. The optimized sample pre-treatment method saves energy, reagent and sample consumption, and reduces secondary pollution and actual loss.