Abstract： Glacier thickness is a fundamental parameter for evaluating glacier dynamics and predicting their future evolution under climate forcing. It is also a key indicator for determining regional water resource supply and maintaining ecosystem stability. As a core region of the Qinghai – Tibet Plateau and an important component of the “Asian Water Tower,” the Qiangtang Plateau plays a crucial role in regional hydrology and ecological security. Changes in glacier storage in this region have significant implications for water resource availability and environmental stability. In this study, we integrated Ground Penetrating Radar (GPR) observations with the Open Global Glacier Model (OGGM) to reconstruct the spatial distribution of ice thickness for Qiangtang Glacier No. 2 and to estimate its total ice volume. Furthermore, future glacier evolution from 2020 to 2100 was projected using climate forcing data from three Shared Socioeconomic Pathway (SSP) scenarios of CMIP6. The GPR measurements revealed an average ice thickness of 107.1 m at the survey points, with a maximum thickness of 161.1 m at an elevation of 5 621.9 m. Building upon these observations, the OGGM simulation yielded an average glacier thickness of 87.7 m and an ice volume of approximately 0.331 km3. Comparative analysis showed a high correlation (0.9702) between the modeled and GPR-measured thicknesses, with a mean error of 3.2 m and a root mean square error of 18.52 m, indicating that OGGM performed with the highest accuracy among the models evaluated for this glacier. Future projections under the SSP1-2.6, SSP3-7.0, and SSP5-8.5 scenarios consistently indicate a sustained and pronounced retreat of the glacier. Mass thinning predominates through 2050, followed by significant area loss toward 2100. The SSP5-8.5 scenario shows the fastest decline, with the glacier effectively melting away by 2070. Under SSP3-7.0, retreat starts slowly but accelerates, resulting in losses of 97.9% in area and 98.7% in volume by 2100. Notably, even the low-forcing SSP1-2.6 scenario predicts a 73.3% area loss and a 96.7% volume reduction by 2100. The findings of this study provide a scientific basis for evaluating glacier water resource changes on the Qiangtang Plateau and contribute to improving the understanding of the evolution processes and climate responses of extreme-glaciers.