Abstract: Using the AlphaGUARD P2000 portable measuring radon instrument to regularly measure the soil radon of the Baodi fault, we determine a scientific and effective soil radon observation method for the area, and analyze the relationship between soil radon concentration and influencing factors, including soil property and moisture, fault structure and activity. We obtain the characteristics of data changes in the research area of the Baodi fault, which has reference value for the application of soil radon observation in seismic monitoring and fault activity tracking. In addition, these results further provide new observation methods and application examples for earthquake situation tracking and anomaly identification.