--- - |2- Abstract In this study, a carboxymethyl chitosan derived from silkworm pupa (SP‐carboxymethyl chitosan) was prepared. The physical characteristics of the SP chitin, chitosan, and carboxymethyl chitosan were analyzed. The scanning electron microscopy results showed that the surfaces of the samples from SP were more uneven, with more surface fractures compared with those of the reference substance (RS). Thermal analysis, X‐ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy analysis showed that the main molecular chain structures of SP samples and RSs had no substantial differences. However, the crystallinity and thermal decomposition temperature of the SP samples were lower compared with those of the RSs. All of these results provide a theoretical basis for the development of applications for the SP‐carboxymethyl chitosan. - Archives of Insect Biochemistry and Physiology, Volume 99, Issue 2, October 2018.