Abstract: The assessment of Ecosystem Service Value (ESV) in high-altitude and remote regions presents substantial complexity, as it is comprehensively affected by multiple interrelated factors including geographical disparities, spatial heterogeneity of ecological environments, and differentiated levels of regional socio-economic development. To achieve a scientific and accurate evaluation of the ESV for the Mapangyong Cuo International Important Wetland in Xizang, this study systematically applied three mainstream evaluation approaches, namely the equivalent factor method, the integrated valuation of ecosystem services and tradeoffs (InVEST) model, and the benefit transfer method, and conducted a rigorous comparative analysis on the evaluation outcomes generated by these distinct methodologies. The research results demonstrated that the total ESV of the Mapangyong Cuo Wetland ranged from 23.847 billion yuan to 29.899 billion yuan, with a calculated average value of 26.873 billion yuan. In terms of specific ecosystem services, the average value of soil conservation service was quantified at 239 million yuan, and the average value of carbon sequestration service stood at 175 million yuan. When adopting the equivalent factor method for evaluation, the total ESV of all ecosystem types within the wetland was estimated to be 23.847 billion yuan, among which the wetland ecosystem itself contributed an overwhelmingly dominant proportion of 96.51% to the total value. Meanwhile, the InVEST model enabled detailed biophysical quantification and corresponding monetary valuation of key ecosystem services: the water yield was calculated as 3.50×10⁴ cubic meters with a monetary value of 146 600 yuan, the carbon storage amounts to 1.22×10⁶ tons valued at 32 million yuan, and the soil retention reaches 2.84×10⁶ tons with a value of 223 million yuan. A critical comparative analysis of the results revealed that the soil retention value estimated by the InVEST model was generally consistent with that derived from the equivalent factor method, whereas the carbon storage estimation obtained from the InVEST model was notably lower. In contrast, the benefit transfer method yielded the highest total ESV of 29.899 billion yuan among the three applied methods. Given the observed discrepancies in evaluation results across different approaches, it is strongly recommended that ESV assessments for alpine wetland ecosystems fully integrate distinctive regional characteristics such as extreme high-altitude conditions and ecological vulnerability. A comprehensive framework combining multiple evaluation methods should be adopted, and targeted adjustments, calibrations, and localizations of model parameters and index systems are essential to reduce evaluation biases caused by relying on a single method. This scientific and rational evaluation strategy is critical for precisely reflecting the authentic service value of wetland ecosystems, and it can provide solid and reliable data support for the formulation of ecological compensation standards and the effective implementation of environmental protection policies for plateau wetlands in Xizang.