Analysis of high precision aeromagnetic data and inversion of Curie isothermal surface in the Hainan Island are of great significance for the study of its deep thermal structure and the adjacent South China Sea continental margin. In this study, the magnetic anomaly characteristics and spatial distribution of the different tectonic units in the island are analyzed by pole and extension processing of aeromagnetic anomaly data. On this basis, the Curie depth distribution is calculated by the power spectrum method inversion. Based on the regional geological evolution, geothermal value, Moho and lithospheric depth changes and seismic sounding profiles of the Hainan Island, the following conclusions are drawn: ① the characteristics of aeromagnetic anomaly in Hainan Island mainly show nearly E- W and NE trend. The nearly EW magnetic anomaly belt is interrupted and disturbed by the NE anomaly belt, indicating that the near E- W trending structural belt is obviously earlier than the NE- trending structural belt. ② The depth of Curie isothermal surface varies from 16 to 34 km, with an average depth of 24 km. The depth of the Qiongbei Cenozoic volcanic- sedimentary basin is obviously deeper, roughly equal to the depth of Moho, and the deepest reaches to 35 km; the corresponding geothermal flow value is relatively lower. ③ The Curie isothermal depth in the Qiongzhong- Wanning and the Dongfang- Changjiang folded regions is obviously shallower, the shallowest is only 16 km, which is obviously lower than the Moho depth in this area, and has relatively higher regional heat flow value. ④ Based on the estimation results of this paper and the results of previous studies, it is shown that the lithospheric thickness of the Hainan Island is 55~90 km, which is a typical rootless and thinned lithosphere. The temperature of Moho in the Hainan Island is 600~900 ℃, and the locally abnormally high Moho temperature may be related to the heat supplied by the replacement of the ancient lithospheric mantle by the asthenospheric mantle in this area.