Abstract: The activities of enzymes in barnyardgrass treated with the diluted extracts of rice accessions were determined during the weed seed germinating courses. the highest inhibitory effect on activity of SOD in shoot was 27.7%,and in root was 38.4%;the highest inhibitory effect on activity of CAT in shoot was 56.4%,and in root was 62.4%.It indicated that rice allelopathy had some physiobiochemical characteristics such as deteriorating the weed plant membrane,affecting the growth and photosynthesis of receiver plant and so on.