In order to find the relationships between the crystal size and the physical & mechanical properties, and to improve the levels of high value-added processing and utilizing for Chinese rattan resources, the daemonorops margaritae, Chinese unique rattan, was chosen as the research material, then the crystal size was measured and analyzed through the X-ray diffraction method before and after gamma-ray irradiation. The results show that the crystal width is in the range between 1.901 and 3.019 nm, and the average width is 2.403 nm. The crystal length is in the range between 4.118 and 28.824 nm with an average length of 10.907 nm. After irradiation, the width of daemonorops margaritae is in the range between 2.139 and 3.540 nm, and the average width is 2.569 nm, and the crystal length dramatically changes in the range between 5.765 and 38.432 nm with a mean of 15.530 nm. Both of the scope and the mean value of the crystal width and length increase after irradiation.