Abstract: Geothermal heat flow is a 'window' for glimpsing the Earth's internal heat, clearly reflecting various processes and energy balance information from the Earth's depths. As an important component of geothermal heat flow, sedimentary layer heat flow can effectively promote the thermal evolution of organic matter in deep and ultra-deep source rocks in sedimentary basins. Rock radiogenic heat production rate, as an important thermal property parameter, is one of the basic parameters for studying sedimentary layer heat flow. The author used natural gamma logging values from 22 drilling wells in different tectonic units of the Qiongdongnan Basin, and calculated 5, 364 radiogenic heat production values using the GR-A empirical formula proposed by various scholars. By comparing these calculations with actual measurements, a columnar representation of the radiogenic heat production rates of the Qiongdongnan Basin was established. Based on these calculations, the heat flow of the sedimentary layers in the Qiongdongnan Basin and its proportion in the surface heat flow were estimated, along with the heating effect of radiogenic heat production on deeper strata. The final results show that the average radiogenic heat production rate of the sedimentary layers in the Qiongdongnan Basin is 1.87±0.51μW/m³ with lithology having a significant impact. Among them, the highest average radiogenic heat production rate is in shale, at 1.97μW/m³, while the lowest is in limestone, at 1.44μW/m³. The average rates for other rock types such as siltstone, fine sandstone, medium sandstone, coarse sandstone, and conglomerate are 1.75μW/m³, 1.60μW/m³, 1.49μW/m³, 1.48μW/m³, and 1.66μW/m³, respectively. Based on the calculated average radiogenic heat production rate of the sedimentary layers, the average heat flow of the sedimentary layers in the Qiongdongnan Basin was calculated to be 18.7mW/m², accounting for 24.8% of the total surface heat flow. The distribution of sedimentary layer heat flow is consistent with the characteristics of sedimentary layer thickness; the contribution of radiogenic heat production to the geothermal gradient of deeper strata is calculated to be approximately 8.9°C/km. Therefore, the radiogenic heating of sedimentary layers has a significant impact on the geothermal field distribution in the Qiongdongnan Basin and should not be overlooked in related studies.