The diffusion and reaction behaviors of disperse reactive dye in polyamide were investigated on the basis of the diffusion theory accompanied by the simultaneous chemical reaction with substrate. Principal three parameters, the surface concentration, diffusion coefficient, and reaction rate constant were determined from the experimental concentration profiles of active dye. It was generally obtained that these three principal parameters were greatly influenced by the change of temperature. The pH of dye bath shows no significant role in diffusion behavior, but the reaction rate constant depends on the pH of dye bath.