Abstract: When dyeing fiber in alkali bath,part of reactive dyes will be hydrolyzed and then become inactivated.Since the inactivated dyes have a similar structure to that of acid dyes,they can be utilized to re-dye the fiber by changing the power of hydrogen of the dyeing bath,so called the denaturated bath.This dyeing process can enhance the dye up-take rate and reduce the discharge load of effluent.Experiments show that good result has been achieved when the bi-component soybean protein/PVA hybrid fiber is dyed by the denaturated bath of reactive dyes.