Abstract: The physicochemical properties of cold seep sedimentary environments are highly dynamic; studying their biogeochemical processes is crucial for understanding the environmental impact of methane seepage. Using the "Shenhaiyongshi" manned submersible, we collected push-core sediment samples from the Haima cold seep in the Qiongdongnan Basin, South China Sea, and compared the applicability of HR-Peeper and traditional Rhizon methods in pore-water sampling. Results demonstrate that HR-Peeper enables precise millimeter-scale (5 mm) resolution measurements of key parameters, including anion and cation concentrations, dissolved inorganic carbon (DIC) concentrations, and carbon isotope compositions. This method provided a clearer depiction of elemental fluxes and the transformation of authigenic carbonate mineral phases in cold seep environments. Compared to the Rhizon method, the HR-Peeper exhibited superior resolution and accuracy in characterizing sulfate-driven anaerobic oxidation of methane (SD-AOM) and carbonate precipitation mechanisms. In addition, we found that carbonate minerals precipitated primarily as aragonite in surface sediments and the aragonite transitioned to high-magnesium calcite at greater depths, which was clearly observed in the vertical profiles of calcium, magnesium, and strontium ion concentrations. The HR-Peeper showed significant advantages in high-resolution pore-water studies, offering a reliable technique for evaluating element fluxes at the sediment-water interface, tracing carbon sources, and investigating authigenic carbonate systems. These findings contribute to a deeper understanding of the biogeochemical processes associated with submarine methane seepage.