Abstract: In order to analyze and evaluate the resist ability of cotton seedling to wind and sandstorm damage in Xinjiang, China, the bending resistance strength and shearing resistance strength were determined by experiments for cotton stem in its seedling stage rather than maturity period. The bending force and shearing force were measured by using a universal testing machine TMS-PRO with a specialized three-point fixture, and the bending resistance strength and shearing resistance strength were calculated from these data. The experiments were conducted at different stage of cotton seedlings life. The shearing force and bending force of cotton seedling stem increases with the age, but it is not obvious in the first five weeks. The results show that the five weeks old cotton seedlings are still weak against external damage, the maximum bending force that a cotton seedling stem can be suffered is 1.98 N and the maximum shearing force is 101.93 N. After five weeks, these values climb rapidly, and they reach to 68.27 and 622.77 N respectively in the ninth week.