Carboxylated cellulose nanocrystals (CCN) and cellulose nanocrystals (CNC) were prepared from borer powder of bamboo by two different kinds of procedures: one-step approach with ammonium persulfate for CCN and two-step approach with sulfuric acid for CNC. The obtained samples were characterizated by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. The results show that the particles of CCN and CNC present spherical shape with diameters of 20-50 and 20-70 nm, respectively. The crystallinity of CCN and CNC is significantly improved after a series of chemical treatment, which is up to 62.75 and 69.84 %, respectively. The research indicates that the borer powder from bamboo could be an excellent raw material for manufacturing CNC in a low-cost and environmental-friendly way. Rational and sustainable utilization of the bamboo borer powder to develop new bioproducts holds great potential value for industry and offers many benefits and opportunities.