[Objectives] Heavy metals are widely present in the marine environment. Due to their long lifespans and habitat fidelity, sea turtles can accumulate heavy metals over time, which poses a threat to their health and reproduction. In recent years, the levels of certain heavy metals in the marine environment of the South China Sea have exhibited an upward trend. High concentrations of heavy metals have been detected in the tissues of stranded sea turtles in the northern South China Sea. However, there have been few studies on the accumulation of heavy metals in sea turtles in the coastal areas of Hainan Island and the Xisha Islands. These two areas are crucial foraging and nesting grounds for sea turtles in the South China Sea. [Methods] Between 2019 and 2022, eight Green Turtles Chelonia mydas and 3 Hawksbill Turtles Eretmochelys imbricata were collected by rescue organizations in Hainan Province. These stranded sea turtles were dissected, and the liver, kidney, muscle, and fat tissues were collected for measurement of the contents of 12 elements (Zn, Cu, Fe, Mn, Pb, Cd, Cr, Ni, Ba, Sr, As, and Hg). Principal component analysis and Friedman test were performed to examine variations in heavy metal contents among four tissues. Spearman’s rank correlation coefficients were calculated to assess the relationships between heavy metals in the two species of sea turtles. Non-parametric Mann-Whitney U tests were employed to evaluate differences in cumulative heavy metal percentages between the two species. [Results] Fe, Zn, and Cu were the most abundant elements in sea turtle tissue, with concentrations ranging from 51.20 to 915.00 μg/g, 27.00 to 146.00 μg/g, and 3.36 to 68.00 μg/g, respectively. In contrast, Cd, Pb, and Hg were present at lower levels, with concentrations ranging from 0.013 to 1.500 μg/g, 0.027 to 0.159 μg/g, and 0.009 to 0.326 μg/g, respectively. In addition, the concentrations of heavy metals in the livers and kidneys of Green Turtles were higher than those in Hawksbill Turtles. This may be attributed to the different pollution levels of their habitats. Significant differences were observed in the concentrations of most elements among the four tissues of sea turtles:Hg, Mn, Fe, and Cu were the highest in the liver; Pb and Cd were the highest in the liver and kidney; Ni was the highest in the kidney; As was the highest in the muscle; and Zn was the highest in the fat (Figs. 1, 2). Furthermore, significant correlations were identified between certain non-essential and essential elements in the tissues of sea turtles (Appendix 5). These elements may share common origins or employ similar detoxification mechanisms in turtles, thereby necessitating further investigation. [Conclusion] In this study, we present the first report on the concentrations and tissue distribution of 12 heavy metal elements in turtles stranded along the coast of Hainan Island and the Xisha Islands in the South China Sea. These results offer a scientific basis for the environmental protection and management of sea turtle habitats in the South China Sea.