This study is to discuss the change of the strength properties of Kevlar fabric which in H2SO4, HCL and NaOH for six month latter. To analyze the reason of fiber damages and change of the strength properties caused by damages of Kevlar fiber in H2SO4, HCL and NaOH for six month latter. From experiment formula, the influence of strength changed caused by C=O bond in chemical structure of Kevlar had be destroyed after soaking in, for six month later. The strength of H2SO4 for six month latter decrease 48, which of HCL decrease 36%, which of NaOH decrease 28%.
