Abstract: The strong acidic ion exchange fibers with higher exchange capacities up to 3.2 mmol•g^-1 were prepared by the dehydration reaction of polyvinyl alcohol(PVA)fiber followed by sulfonation.The paper studied the effects of dehydrating catalyst，temperature,and atmosphere on dehydration reaction and the effects of mass loss, temperature and time of sulfonation on exchange capacities.The IR spectra showed that the dehydrated fiber exhibited the absorption peak of carbon double bond.There were absorption peaks of S=O and C=S in the IR spectra of the product.The spectrogram of electron diffraction indicated that the fiber could keep its crystalloid structure by drawing tension.