Using Konjac glucomannan as the raw material,energetic glucomannan (EKGM) was synthesized in the mixture of fuming nitric acid,concentrated sulfuric acid and phosphoric anhydride,and was characterized by elementary analysis,FTIR,SEM,XRD and TG-DSC. The results indicate that the nitrogen content of EKGM is 13.59% due to the presence of —ONO₂，and crystallinity is higher than that of original KGM because of a loose network structure and the decomposition temperature is 161 ℃ with a high exothermic peak.