<p>Numerous sandstone cultural heritage artifacts excavated and preserved along the Silk Road have experienced millennia of environmental weathering and exhibit diverse weathering patterns. As a key component of microstructure, the pore network plays a critical role in the weathering process of sandstone. However, comparative studies on sandstone microstructural evolution across different weathering patterns remain limited. To address this gap, this study investigates weathered sandstone from the Ancient Rope Bridge Ferry. By combining mercury intrusion porosimetry (MIP) and micro-computed tomography (micro-CT), the microstructural characteristics of sandstone under various weathering patterns (crack, delamination, powdering, and scaling) and degrees were examined. Voids were classified based on their shape factor and diameter, and the evolutionary characteristics of fractures and pores were systematically investigated. Results indicate that both porosity and pore size increase with weathering. Crack, delamination, and powdering samples exhibit void heterogeneity, with fracture propagation as the primary mechanism and pore coarsening as a secondary process contributing to increased porosity. In scaling samples, porosity changes are mainly driven by fracture propagation. Fractal analysis identifies key stages in the weathering process: crack samples show evident changes at intensively weathering stages, delamination and powdering samples exhibit structural deterioration at moderately stages, while scaling samples show localized surface microstructural deterioration. By integrating MIP and micro-CT, this study introduces a novel approach to calculate total porosity, providing a more comprehensive method for assessing weathering. Finally, practical recommendations for conservation strategies of sandstone cultural heritage artifacts are provided.</p>