This article discusses the geochemical features of the fault gas radon (Rn) in the Jiangsu section of the Tanlu fault zone. The Rn concentration across the fault was measured at four locations: Chonggang, Xiaodian, Qiaobei, and Hezhuang. Measurement results showed that the Rn concentration anomaly contrast in the Jiangsu section of the Tanlu fault zone was 2.05~5.73. The Rn concentration was mainly distributed in and near the fault zone and showed a good correlation with seismic activity.