Mangrove plants, as key components of wetland ecosystems, have their distribution limited by low temperatures. Kandelia obovata, growing at the northern edge of its range in China, can regulate gene expression without altering DNA sequences to adapt to environmental changes when subjected to adverse stimuli. This study conducted whole-genome bisulfite sequencing on Kandelia obovata populations across a 10-site latitudinal gradient from Hainan to Zhejiang, aiming to elucidate the epigenetic adaptation mechanisms of artificially northward-transplanted populations. The results showed that: DNA methylation levels in natural populations of Kandelia obovata along China's coast significantly increased with rising latitude, whereas artificially transplanted populations maintained stable methylation levels. Compared with the Fujian mangrove forest, the number of downregulated Differentially Methylated Regions (DMRs) in Zhejiang's transplanted populations increased with latitude, and DMR-associated genes were enriched in cold resistance pathways such as aromatic amino acid biosynthesis. This study, from an epigenetic perspective, reveals that artificially northward-transplanted Kandelia obovata may actively demethylate to reconfigure its cold resistance regulatory network, providing an epigenetic basis for the conservation of northward-expanded mangroves.