The implementation of deep storage technology for high-salinity water in coal mines offers significant potential for reducing the costs of wastewater treatment, thus expanding its practical application. However, the lack of rapid and reliable monitoring techniques presents a challenge in verifying the distribution of high-salinity mine water after sequestration, which in turn hinders further sealing operations. To address this limitation, this study investigates the use of the Wide-Field Electromagnetic Method (WFEM) for assessing the sequestration of high-salinity water in Dongsheng Coalfield (Ordos). By leveraging the underground electrical structures identified by WFEM, and integrating petrological analysis with the Archie equation, we monitored the diffusion range of the high-salinity water. The correlation between the low-resistivity range and high-salinity water volume is validated. Our results demonstrate that WFEM is effective in detecting low-resistivity zones, and the estimated water volume (555,000 to 645,000 m
3) closely aligns with the actual sequestration volume. This approach provides a robust method for evaluating the effectiveness of geological sequestration, offering valuable insights for the management of high-salinity water storage.