Abstract: This paper proposes an unpowered dust concentration detection technology based on Mie scattering method. Through the experimental comparative study of the unpowered key position and the diameter and length of the unpowered through hole, the size of the unpowered mechanism is optimized; the factors of dust concentration were analyzed experimentally, and the algorithm was compensated. After the study of unpowered size and analysis of influencing factors, the unpowered unit can be more suitable for on-site detection, the detection error is smaller, the maintenance time is extended, and the practicality is improved.