Abstract: Leather cultural relics carry valuable insights into ancient history and culture, and their archaeological excavation and scientific conservation are crucial for cultural heritage preservation. Tanning constitutes the critical step in leather production, where the selection of tanning agents and the intensity of tanning effects directly determine the properties and preservation status of leather cultural relics. However, current research in this domain remains insufficient. This study systematically reviewed analytical techniques for tanning agent identification in modern leather and leather cultural relics, while providing an in-depth exploration of multi-dimensional approaches for assessing tanning effects including tanning intensity, hierarchical structure and pore properties of leather. Based on cutting-edge research and practical applications, a methodological framework for tanning agent identification and tanning effect analysis in leather cultural relics was proposed. It provides critical support for developing the assessment protocols of the deterioration of leather cultural relics and elucidating the mechanisms of collagen stabilization by historical tanning agents.