Analyzing the δ13C-DOC in high-salinity water remains challenging due to significant differences in interfering ions and analyte concentrations. In this study, halide interference was eliminated using an AgF solution to generate AgCl precipitate, and the δ13C-DOC was measured using a GasBench Plus preparation device coupled with isotope ratio mass spectrometry (IRMS), establishing an accurate and sensitive method to determine δ13C-DOC in high-salinity water samples. The external accuracy of the method was 0.09‰, and the difference between the measured and certified δ13C values of IAEA-601 was 0.14‰. When the carbon content of the sample was 2.0 μg (equivalent to 0.5 μg mL-1 DOC content in the sample), the precision was 0.11‰ with a 0.15‰ difference. The interference of various NaCl concentrations on the measured δ13C-DOC was evaluated, and 200 g L-1 NaCl produced an approximately -13.97‰ difference between the stable isotope result and its true value. This difference was observed when we analyzed saline samples without any measures to deal with salt interference. However, this difference was overcome using the presented procedure. The δ13C-DOC of twenty-one high-salinity water samples was determined using the proposed procedure and a total organic carbon analyzer with a high-temperature catalytic oxidation unit coupled to IRMS. The δ13C-DOC results obtained using the two methods are consistent, with differences of -0.17‰ to -0.40‰, indicating that the influence of halides is completely overcome by the proposed procedure. Therefore, the proposed method enables the analysis of the ??13C-DOC in high-salinity water regardless of the type and origin of the salt solution, provided the concentrations of DOC are between 0.5 to 50 μg mL-1, and shows great promise in allowing many labs that are currently limited to analyzing freshwaters to expand their capabilities.