Abstract: There are big differences on silk fabrics both from the respect of microcosmic and macroscopy between two batches of silk products, one unearthed from the tomb with the age of Chu Dynasty in Jin Zhou and the other unearthed from Ming tomb with the age of Ming Dynasty which is almost two thousand years after Chu Dynasty in Nan Chang. Methods applied to analyze the status of ageing and degradation on these products includes morphology analysis, infrared spectrum analysis, X-ray diffraction analysis, thermo gravimetric analysis, and amino acid analysis. Analysis results indicate that: it is more serious on silk ageing and degradation of the product in Jin Zhou, mainly including of embitterment and severely destroyed surface, the redshift of amideⅠ absorption peak caused by partial destroys of hydrogen bond in molecule of silk protein peptide chain, increase of plain woven fabric, decrease of degree crystallize degree, decrease of the ability to resist heat because of ageing and degradation for long. Both have partly degradation of amino acid in amorphous area. The products in Nan Chang have hydrolysis of ageing with silk fabric, mainly occurred in amorphous area.

Key words: ilk fiber, ageing and degradation, crystallinity, heat resistance, amino acids