As an important component of Thangka cultural relics, mounting and frame inlaying materials hold significant value. Among a set of Thangkas depicting Master Tsongkhapa’s Five Visions in the collection of Xizang Museum, two Thangkas exhibited various forms of deterioration in their original mounting materials, including insect damage, losses, cracking, soiling, discoloration, and fading, which seriously affected the integrity of the cultural relics. Based on a detailed condition survey and scientific analysis, this study carried out conservation treatments aimed at preserving the original materials. The process included cleaning, disassembly, dyeing, humidification and flattening, and localized repairs. These interventions restored the Thangkas’ original visual appearance, stabilized their structure, and preserved the integrity of the entire artworks, enabling improved exhibition, storage, and long-term conservation.