Abstract: Abstract: Changes in the photosynthetic characteristics in winter wheat ( Triticum aestivum L.) flag leaf with different soil tillage methods under control and ultraviolet-B enhanced radiation (UV-B, 280-320nm) were investigated. The field experiment was carried out in Nanjing, China. It lasted two years. The experiment included three tillage methods: conventional tillage (moldboard plow, 25 cm of tillage depth), minimum tillage (rotary tillage, 10 cm of tillage depth), and no-tillage (0 cm of tillage depth) for wheat cultivation. Minimum tillage and no-tillage methods were conservation tillage methods. Artificial UV-B radiation was used to simulate the enhancement of UV-B radiation. The supplemental UV-B radiation was supplied with the UV-B lamps (40 W, peak of lightwave is 313 nm). The level of UV-B irradiance supplemental was equivalent to an enhancement of 20% above the control treatment. The photosynthetic rate, photosynthesis - light response curve, chlorophyll content, superoxide dismutase (SOD) activity, malonaldehyde (MDA) content, and soluble protein content in winter wheat flag leaf were determined in the experiment. The results showed that: Under the 20%-enhanced UV-B radiation condition, the yield of winter wheat for minimum tillage and no-tillage methods increased by 1632.12 and 952.15 kg/hm2, respectively, both significantly higher than that of the conventional tillage method. Analyzing from the photosynthesis, the photosynthetic rate, apparent quantum yield (AQY), maximum photosynthetic rate (Pmax), chlorophyll content, SOD activity and soluble protein content of flag leaf for minimum and no-tillage methods were significantly higher than that of the conventional tillage method, but the MDA content was lower at 15 days after wheat anthesis, and the senescence degree of wheat flag leaf was significantly lower than that of the conventional tillage method. It was considered that the higher photosynthetic capacity and lower senescence degree of wheat leaves during grain-filling period of two conservation tillage methods was a key reason for their higher yield than that of the conventional tillage method.