Abstract: The detection and control of molten steel level is one of the key technologies in the continuous casting process. At present, the radioactive isotope Cs137 molten steel level measuring device is widely used in China, but it is radioactive and has radiation damage to humen health. In response to this problem, based on the principle of electromagnetic induction, the electromagnetic molten steel level detection device which was safe and met the requirements of detection accuracy was developed. First of all, in the finite element simulation software of electromagnetic field, the control variable method was used to optimize the design of electromagnetic detection sensor composed of an excitation coil and two differential induction coils. Then, a molten steel level detection instrument with two sensors was developed, and the induced voltage signal fed back by the sensor was converted into the measured value of molten steel level after the algorithm of piecewise linear interpolation. The experimental results showed that the molten steel level detection device can measure strong and weak magnetic materials. The range of a single sensor was 26 mm, the accuracy can reach 1 mm, and the response speed was 0.5 s, which met the requirements of molten steel level detection performance.