Abstract: The aim of this study was to gain some insight into the kinetics of reactive dye when uptaking on the fiber. The methanolysis and hydrolysis of monochlorotriazine C.I. Reactive Yellow 2 in basic methanol & water solution under different conditions were studied, and the rate constants of these reactions, when pH=10, were also determined. It was found that when the temperature at 80℃ and pH = 9～12, the methanolysis efficiency decreased as the time increased, and higher the pH value, faster decreased the methanolysis. Increasing pH value was disadvantageous to alcoholysis, i.e., the superiority of alcoholysis reaction of dye lowered and, when pH=10, the methanolysis reaction rate contants were 2-3 times of that of hydrolysis reaction under 50～70℃, but were almost equal to that of hydrolysis reaction when the temperature was 80～95℃. It was also found that both the methanolysis and hydrolysis reactions were pseudo-first-order reactions.