Cellulose nanofibrils (CNFs) were obtained through one-step mechano-partial dissolution by ball milling in N, N-dimethyl acetamide with a low concentration of LiCl from agricultural waste bagasse pith (BP). Compared with fibrous cellulose, parenchyma cellulose (PC) is less uniform in diameter and less aligned, causing PC to dissociate into CNFs during this process without pretreatment. The results showed that the CNFs prepared from PC of BP had a diameter of 30-200 nm and a length of several micrometers. The as-obtained CNFs, along with dissolved cellulose, formed a wet-stable and highly transparent nanopaper in a sorbitol aqueous solution bath, which exhibited a high strain of 101% and a low Young's modulus of 4.3 MPa owing to the addition of the plasticizer sorbitol. This type of nanopaper with favorable transparency, high tensile property, and low Young's modulus has great potential for use as electronic skin and medical dressing material.