Abstract: Kevlar fibers were subjected to the exposure of the ultraviolet radiation and the treatment of sulphuric acid,NaOH,and NaCl with various concentrations and under different temperature respectively.Tensile strength of the treated fiber was tested.It was found that the tensile strength of the treated fiber was greatly reduced.The research also revealed that NaOH,sulphuric acid and NaCl solution with certain concentrations would cause serious damage to the Kevlar fiber.