Abstract: For the problem of measuring the decrease in the accuracy of low-concentration dust based on the principle of electrostatic induction， under the condition of a certain inlet diameter， the length of the constriction section， the length of the throat section， the diameter of the throat section， and the length of the diffusion section are the design variables， and the induced charge quantity is used as the response variable， To study the structure of the measuring device that maximizes the amount of induced charge， the fluid mechanics software Fluent6.3 is used to simulate the internal flow field of the measuring device with different structural dimensions， based on the response surface methodology and the use of statistical software Design-Expert， the throat diameter and the throat length of the measuring device have a significant effect on the induced charge quantity， and the structure size of the measuring device that maximizes the induced charge quantity is obtained；The effect of dust with different particle diameters on the induced charge of the measuring device before improvement is analyzed： when the particle size is small， the effect of the induced charge is small； The structure and dimensions of the measuring device are also different； through comparative analysis， the dust of different particle sizes， the induced charge of the improved measuring device are increased by more than 15%， and the improvement effect is more obvious when the particle size is small.