Abstract: This paper analyzed the basic principle of soot concentration detection based on β-ray method. A sampling gun designed for soot and dust collection was designed according to the emission of soot and dust in the fixed pollution source, the constant speed sampling was realized based on orifice flow technology. In order to ensure the following accurate sampling, the heating and insulation mechanism was designed and the anti-traditional mining integrated body was developed. The test experiment was carried out for 3 months based on the prototype of the direct reading detection technology. The experimental results showed that the detection error was less than 10% during the whole experimental period. The direct detection of soot concentration based on β-ray method can be applied to the rapid detection of soot.