<p>Understanding the extent of cocoon degumming has been a challenge in tracing the geographical origin of silk fabrics. In this context, stable isotope techniques offer a promising approach for tracing ancient textiles, particularly in addressing the controversial issue of silk origin. In this study, modern cocoons subjected to varying degrees of degumming were analyzed using isotope ratio mass spectrometry (IRMS) to investigate the effects of degumming on cocoon-stable isotopes. The results revealed that degumming temperature and duration led to differences in the δ²H, δ¹⁸O, δ¹⁵N, and δ¹³C trends of the samples, with δ²H and δ¹³C becoming depleted, and δ¹⁵N and δ¹⁸O becoming enriched after degumming. These findings indicate that degumming conditions significantly influence the stable isotopes in silk. Overall, this study provides a reference for using stable isotope analysis to trace the source of silk fabrics and other cultural heritage materials.</p>