According to archaeological records, there are a number of well-established dating methods. However, there is a lack of identification of specific type of artifacts, especially collagen-based materials with complex structure. Leather cultural relics, one of representative of collagen-based cultural relics, are precious physical historical materials for the study of ancient social history[1-3]. Leather cultural relic is an important carrier for inheriting human civilization and witnessing historical development. Therefore, the research on the identification and aging mechanism of leather cultural relic is of great significance. In this work, with leathers tanned by tara and quebracho as cultural relics model, the pyrolysis characteristics and kinetics of vegetable-tanned leather were investigated by thermogravimetry (TG) analysis at three different heating rates and the pyrolysis products were analyzed by TG coupled with Fourier transform infrared spectrometry and mass spectrometry (TG-FTIR-MS) analysis, whose micro-loss characteristic is in line with the particularity of cultural relics. The pyrolysis kinetics of the untanned sheepskin and vegetable-tanned leathers were investigated by using both methods of modified Kissinger-Akahira-Sunose (MKAS) and Friedman (FR). The gaseous products mainly consist of CH₄, NH₃, H₂O, CO, HNCO, CO₂, and pyrrole. The results were obtained that the appearance of CO and the intensity changes of CH₄ and NH₃ may provide secure and reliable identification of leather tanned by hydrolyzed and condensed tannins. The leather aging mechanism was revealed, and a new identification method was obtained, which might provide an important theoretical basis for the proper preservation and restoration of collagen-based cultural relics.