According to the Biot-Savart's Law, the principle of the detecting system which measures the grade of the iron concentrate is analysed in this paper. It carries out an analysis of influence of inductance sensor coil structure parameters on the performance of sensor. The finite element model of the air core coil is established and analysis of finite element simulation is done to inductance sensors by using orthogonal method. According to different structural parameters, the relation of magnetic permeability of the iron concentrate and the inductance of the sensor coil can be established. Moreover, the effect of the sensor coil’s parameter on the linearity and the sensitivity of the sensor can also be determined. All the above provide a reference for the design of coil structure parameter of the inductance sensors.