Abstract: Determining the content of silicon in Si-Mn ferroalloys was investigated by a novel resistivity measurement technique, which is based on the single-valued change of electrical resistivity with the content of one alloy element in a quasi-binary alloy. The relationship between silicon content and electrical resistivity in Si-Mn alloys was obtained by a series of experiments. It can be expressed as Si%=-12.51+2×10⁷ρ-4×10¹²ρ², When the content of silicon in Si-Mn alloys is less 6%, the ratio of Mn to Fe has little influence on the electrical resistivity. Furthermore, the error in determining the silicon content can be controlled within 0.005% to 0.178%. To avoid the effect of some factors including slag inclusions, voids and other defects on the measuring accuracy, samples applied to measure the electrical resistivity are 6.00 to 6.50 mm in diameter and about 1 cm in length.