Abstract: Abstract:To detect the activities of rice catalase ,ammonium molydate method is accurate, convenient and efficient .The reliability of the method was verified by using flag leaf of Neiliangyou 6 and Xiushui 09 and comparing the accuracy and the precision with ultraviolet absorption method.The first,the average of two method have no significent difference .The second, the Coefficient of Variation of ultraviolet absorption method respectively is 0.78% and 0.58%,and the Coefficient of Variation of ammonium molydate method respectively is 0.35% and 0.42％.