The Mianhuakeng uranium deposit, characterized by uranium-rich granite, serves as a key site for research into crustal radioactive heating. Based on 45 rock samples, this study reviews that the host granite in the Mianhuakeng uranium deposit has a high radioactive heat production rate (avg. 5.50 μW/m3) and a low Th/U ratio (avg. 2.62). Uranium-rich granite and its alteration zone within the upper crust (0–5 km depth) contribute about 45% of the total radioactive heat production, wich is crucial for controlling geothermal resource distribution. For uranium-thermal at tectonic plate margins, a symbiotic geological model was proposed: Firstly, subduction of the Pacific Plate caused upwelling of the asthenosphere, generating a high heatflow background. Secondly, heat transfer is enhanced by major faults such as the Youdong and Mianhuakeng faults. Subsequently, uranium was mobilized, transported, and enriched within the granite through deep siliceous hydrothermal activity and associated alteration. Ultimately, the uranium enrichment in granite leads to increased radioactive heat production, resulting in local thermal anomalies. This model provides a theoretical support for exploring and developing uraniumthermal symbiotic resources in South China.