Abstract: The effects of different nutrient treatments on photosynthetic characteristics，metabolism of active oxygen of rice flag leaves in the latter stage are studied．The results show that the combined application of organic and inorganic manures，especially barn yard manure and chemical fertilizers can significantly delay the decomposition of chlorophll and the decrease of photosynthetic rate of rice flag leaves．In the meanwhile，the activities of superoxide dismutation(SOD)and catalase(CAT)and the increase of content of malondialdehyde(MDA)are controlled and adjusted resulting in the increa ses of the grain weight and grain yield．