Abstract: 2-acrylamido-2-methyl propane sulfonic acid(AMPS) was grafted onto the knitted cotton fabric by argon microwave plasma.The formation of the grafted fabric surface was confirmed by IR spectra.The grafting process conditions were optimized by orthogonal design,variance analysis and mathematical statistics method.The surface morphology,hydrostatic pressure,moisture permeability and bursting strength of the knitted cotton fabric before and after grafting were examined.The results show that the hydrostatic pressure of the grafted wet fabric increases greatly and it responds smartly to the change of moisture at the environment,whereas the grafted dry fabric shows slight decrease in moisture permeability and the bursting strength.