The eri-silk was degummed by Alkaline protease,the chemical composition of the eri-silk was analyzed and the internal structure of the retting eri-silk was analyzed by infrared spectral, also the vertical form of the was tested by electron microscopy and using thermal analysis to study the thermal properties of the eri-silk. The results showed that the highest content in the eri-silk was alanine, followed by acetic acid; The heat resistance of the eri-silk was worse than the soybean protein fiber and wool, the the surface of the degumming eri-silk was smooth, there was obvious dents between two silk fibroin; the structure of the eri-silk fibroin contain α-helix and β-folding structure which is the most main structure, there is distinguishing peak characteristics of AmideI at wave 1661.