The sample was dissolved with HNO₃ and HF system. The mass spectrometry interference was corrected and eliminated by selecting proper isotopes and adopting interference coefficient method. ⁴⁵Sc was used as internal standard to determine Li, B, Mg, Al, P, Ca, V, Cr, Mn, Co, Ni, Cu and Zn, and ¹⁰³Rh was used as internal standard to determine Ga, Cd, Sn, Sb, Ba and Pb. Consequently, a determination method of 20 impurity elements in nanometer silica fume by inductively coupled plasma mass spectrometry (ICP-MS) was established. It was found that the volatilization loss of B could be effectively inhibited by adding 1.0mL of 30g/L mannitol solution in sample dissolution and meanwhile controlling the evaporation digestion temperature at 120℃, thus improving the determination accuracy of B. After sample treatment by heating and evaporation digestion to remove silicon, the mass concentration of silicon in test solution was less than 100mg/L. Therefore, the interference of determination by silicon matrix could be eliminated. Moreover, the interference on determination of P was eliminated. The memory effect of B could be eliminated by increasing pump speed and alternating rinsing with 10% (V/V) ammonia water and 10% HNO₃ (V/V). The calibration curves were prepared with the mass concentration of elements as abscissa and the corresponding ion strength as ordinate. The correlation coefficients of calibration curves of all elements were higher than 0.9999. The detection limits of method were between 0.0003μg/g and 0.30μg/g. The background equivalent concentration was 0.0011-4.9μg/g. The experimental method was applied for the determination of elements in actual sample of nanometer silica fume. The relative standard deviations (RSD, n=9) of determination results were between 1.1% and 7.6%. The recoveries of standard addition were between 90% and 108%. The inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for comparison test. The results of B, P, Al, Ca, Mg and Fe were basically consistent with those obtained by the proposed method.