Abstract: The content, composition distribution, and source characteristics of n-alkanes in the surface sediments from four mangrove forests of Gaoqiao town, Techeng island, Huguang town, and Jinsha bay of Leizhou peninsula are studied. The results show that the content of total organic carbon (TOC) in these mangrove surface sediments is between 0.10% to 5.62%, and the content of total n-alkanes (∑n-Alk) ranges from 0.69 to 16.60 μg/g(dw). The composition of n-alkanes in these surface sediments is dominated by medium to long chains n-alkanes (n-C₂₃ to n-C₃₁), that are distributed as unimodal patterns. The n-alkanes display a clear odd-even predominance with an exception of samples from Jinsha bay. The composition and distribution of n-alkanes and the principal component analysis of related index of average chain length (ACL), carbon predominance index (CPI), short-chain/long-chain ratio (∑n-C₂₀⁻/∑n-C₂₁⁺), terrigenous/aquatic ratio (TAR), and proxy of aquatic macrophyte input (P_aq) shows that the n-alkanes in mangrove sediments is mainly sourced from higher plants, among these the n-alkanes in Gaoqiao town mangrove surface sediments are mainly originated from the terrestrial higher plant, while the aquatic plant sourced contribution in the Techeng island and some samples of Huguang town are higher, and the mangrove surface sediments in Jinsha bay is effected by human activities. Therefore, we believe that the composition and distribution of n-alkanes in mangrove surface sediments could be used to reflect the characteristic of their source inputs.