The sea sand in the shallow sea around the estuary of Changhua River are rich in resources and of great economic value, but there is no systematic research on their provenance. To solve this scientific problem, U-Pb isotope geochronology and in suit element geochemistry of 1 471 grains of detrital zircons from the coastal sea of western Hainan Island and the estuary of the Changhua River were investigated. The age range of the coastal sea of western Hainan Island is 3.45 Ga ~ 82 Ma, with three major age peaks of 99, 241, 252 Ma, and four minor age peaks of 113, 155, 325, 357 Ma, The age range of the estuary of Changhua River is 2.3 Ga ~96 Ma, with three major age peaks of 101, 244, 254 Ma, and four minor age peaks of 122, 266, 281, 307, 342 Ma. The results show that the sediments in the coastal sea of western Hainan Island are identified by the significant age peak of ~ 99 Ma and the lack of age peaks of Jinninian, Caledonian and Himalayan, and Hainan Island should be its main source area. The difference between the age peaks of the coastal sea of western Hainan Island and the estuary of Changhua River indicates the source contribution from the rivers in the south side of western Hainan Island. The newly identified 380 ~ 310 Ma age group can be used as a source identification marker in the Changhua River Basin. This detrital zircon age spectrum is consistent with several important geological events in Hainan Island, which contributes to the understanding of the complex geological evolution history of Hainan Island.