Abstract: The hydrolysis dynamics of diquat in deionized water,river water and ground water were studied by incubation at 25℃ and the hydrolysis dynamics of diquat at different temperature(10℃,25℃,35℃) in pH 9 were investigated.The degradation was followed by GC.The experimental results indicated that the kinetic process of diquat can be described by the first-order reaction,the hydrolysis rates of diquat in deionized water,river water and ground water were almost the same.The pH was a critical factor of the rate of the degradation of diquat in aqueous solutions.Diquat was stable in acid water and neutral water,but its hydrolysis easily took place in basic water.The higher temperature was helpful for the hydrolysis during the range from 283 K to 308 K in basic water,the activation energy of hydrolysis for diquat was 25.89 kJ/mol,activation entropy was -191.81 J/mol·K,and the temperature coefficient was 1.52.