Terrestrial in situ cosmogenic nuclide(TCN)1⁰Be exposure dating method is currently one of the most successful dating methods for glacier geomorphology, and this technology has made significant contributions to global glacier geomorphological dating. During the dating process, granite samples are usually selected for dating. However, granite exposed over millennia is subject to weathering, which reduces the concentration of cosmogenic nuclide Be-10 on the surface, leading to an underestimation of the exposure age of the landform. Thus, we aim to quantify the erosion rate of granite over millennial timescales to improve the accuracy of cosmogenic nuclide exposure dating. This application is crucial for understanding evolution of glacial landforms. This study focuses on the Paleo-Daocheng ice cap, where the Be-10 exposure dating technique was applied to determine the surface exposure ages of granites with varying degrees of weathering. Six granite samples sites and twelve Be-10 age samples were processed. By combining the weathering thickness difference, the erosion rates of granite samples were estimated. The results from six granite sample sites and twelve Be-10 age samples indicate that the erosion rate of granite in the Daocheng Ancient Ice Cap area ranges from 1.2 mm/ka to 3.5 mm/ka. This study provides a reliable reference for estimating sample erosion rates in cosmogenic nuclide exposure dating.