The thermal properties of rocks are crucial for understanding the characteristics of geothermal fields and play an important role in studying geothermal fields and evaluating geothermal resources. In order to quantitatively understand the thermal properties of rocks and their impact on the geothermal field. This study systematically analyzes the thermophysical characteristics of rocks in Hainan Island through thermal property testing of outcrop samples. This provides new data and references for research in areas related to regional geothermal energy. Our results reveal that: ① Significant differences exist in the thermal properties of the three rock types in Hainan Island. Metamorphic rocks have the highest thermal conductivity (3. 16±1. 41 W/(m·K)), followed by sedimentary rocks (2. 53±0. 80 W/(m·K)), and igneous rocks (2. 40±0. 74 W/(m·K)). Conversely, igneous rocks display the highest heat generation rate (2. 68±1. 68 μW/m3), followed by sedimentary rocks (1. 90±0. 92 μW/m3), and metamorphic rocks (1. 10±0. 95 μW/m3). ② Porosity and thermal conductivity show a negative correlation, while density and thermal conductivity exhibit a positive correlation. Saturation correction of the rock samples significantly increases thermal conductivity values. Based on the specific situation of Hainan Island, we established an empirical formula for saturation correction applicable to the area. ③ U and Th are the main heatgenerating elements in rocks, both exhibiting a strong positive linear correlation with heat generation rate, while K shows a weaker correlation. ④ The varying thermal conductivity and heat generation rates among different strata lead to uneven temperature distribution, influencing the accumulation of strata temperature. Furthermore, temperature field simulations demonstrate differences in results when considering and neglecting rock saturation.