The policy for controlling air particulate matter pollution is becoming increasingly stringent. To address the issue of measurement stability, researchers proposed the sheath flow structure used to limit particle overlap and the pollution of light cavity. To achieve high stability concentration measurement, this paper optimizes the measurement accuracy and antipollution performance of the sensor from three perspectives: optical cavity structure, mass concentration calculation method, and gas path structure. The optical cavity structure is simulated using optical tracing to achieve the best-scattered light collection effect. Modifying the sensor's characteristic parameters reduces its measurement error. The simple sheath gas protection structure with internal circulation mode is designed to reduce measurement error caused by particle overlap and protect the optical cavity. The effect of gas flow rate on the detection results of total dust concentration (TSP), PM₁₀, and PM_2.5 is studied, and the optimal air pump flow rate is set. The experimental results show that the aerosol concentration sensor simultaneously achieves a high stable mass concentration measurement of TSP, PM₁₀, and PM_2.5, and the measurement error is <±5%.