Cladophora has a unique cellulose structure and is easy to extract. In this study, ClaNC was isolated from freshwater green algae (Cladophora glomerata) that thrived in swamps, using hydrochloric acid (HCl) hydrolysis. This study was conducted on the changes of chemical composition, morphology and structure of ClaNC through FTIR, XRD, SEM, and TEM. Lignin removal (peak 1535 cm-1) was effective after HCl hydrolysis, but bands 1028 and 894 cm-1 confirmed the identity of the chemical composition of Cladophora glomerata lettuce which was not lost even at nano-scale. XRD analysis revealed the ClaNC crystal index was 94.0% with a preferred orientation in the lattice plane of Iα [110] and Iβ [200]. The surface morphology of Cladophora raw material is rod-shaped as shown by SEM, with an average diameter of 21.3 (± 1.01) μm, whereas ClaNC refers to nanofibrils with an average diameter of 30.6 (± 0.85) nm as shown by TEM.