Abstract: everal common native cellulose,ramie,flax,cotton,as well as bamboo pulp and hardwood pulp were investigated using13C-CP/MAS NMR spectroscopy and X-ray diffraction,and the differences between two methods were discussed.NMR spectra of these fibers were analyzed in detail and some structure parameters such as crystallinity,lateral microfibril size,and allomorphs content were determined.Crystallinity and crystalline size calculated by NMR method are less than these obtained by X-ray diffraction.The reason is that the intensity of crystalline signal depends on the number of carbon atoms presented within crystallite in13C NMR spectra.