This study is to discuss the change of the bullet-proof of Kevlar fabric which in sea water, bleach and cleanser for four month latter. To analyze the reason of fabric damages and change of the bullet-proof caused by ageing of Kevlar fabric in sea water, bleach and cleanser for five month latter. By the experiment formula, we know that the influence of ballet-proof changed caused by C=O bond of Kevlar fiber had be changed after soaking in sea water, bleach and cleanser for five months latter. The bullet-proof of Kevlar fabric in sea water for four month latter decrease 27%, which in bleach decrease 25%, which in cleanser decrease 17%.
