Abstract: In order to investigate the changes of the protective enzymes activity and their isoenzyme during the differentiation of rice callus, the culture was conducted by using the Xiang early indica 33, 01 early 5202 and V20B. The results as followed: the soluble protein content had a peak value at the 6th and 12th day, that is, forming stage of embryogenic cells and seedling differentiation. Peak value of POD activity appeared at the 12th day after calli inoculation. Changing trend of SOD activity is opposite to POD activity during the calli differentiation. We supposed that the difference of enzyme activity was relative to the determination of cell differentiation. Moreover, changes of POD and SOD isoenzyme was closely relative to the course of calli differentiation in rice.