Abstract: Investigating the concentrations of natural radionuclides in soils is basic for soil pollution prevention and control. First, this study determined the background values and anomaly thresholds of radionuclides ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K in soils in Guangdong Province using the geographic information system (GIS) and three methods, namely conventional statistics, exploratory data analysis (EDA), and median absolute deviation (MAD). Then, this study assessed the radioactivity levels of the soil environment using four indices: the γ radiation dose rate, the equivalent radium specific activity, the external exposure index, and the annual effective dose rate. Finally, this study assessed the health risks of the soil radioactivity using the geoaccumulation index method, the single factor index method, and the Nemerow composite index method. The results indicate that: (1) Radionuclides ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K in soils of Guangdong Province have average concentrations of 79.4, 102.95, 74.59, and 541.25 (Bq·kg^-1·dry), respectively; (2) The four radionuclides have background values of 34.27、46.75、32.87 and 271.79 (Bq·kg^-1·dry), and the anomaly values of 111.35、141.805、105.12、946.26 (Bq·kg^-1·dry); (3) The radioactivity level indices for soil environment, namely D, Ra_eq, Hex, and AEDR, show averages of 121.44 ± 67.08 nGy/h, 263.48 ± 147.72 Bq/kg, 0.08~2.3, and 148.93 ± 82.26 μSv/a, respectively; (4) The radionuclide geoaccumulation index suggests clean soils, the single factor index indicates slight pollution, and the Nemerow composite index of 0.22~5.52 (average: 1.74 ± 0.97) indicates mild pollution. These three indices, which suggest roughly consistent results for the health risk assessment of radionuclides in soils, can serve as a supplement to the health risk assessment method for soil radioactivity.