Abstract: In order to ascertain the mechanism of transgenic hybrid cotton KB02 high yielding, the physiological characteristics of the transgenic hybrid-Bt cotton KB02 F1, KB02 F2, its parents, hybrid Tai-D5 F1 and E-anti-Cotton 13 were studied. The results showed that the turning point from blooming to senescence is at the later full boll stage (about August 17) under our experimental conditions. About September 10, the leaves of POD activity and seed cotton yield was significantly negatively correlated, and the correlation coefficient was -0.8925. With the aging of the plant (August 17 - September the 10th or so), different varieties of SOD, POD activity and MDA concentrations were gradually increased. In late growth of the transgenic hybrid-Bt cotton KB02F1, the chlorophyll content and SOD activity was higher, while the POD activity and MDA content was lower than other varieties, its showed that had anti-senescence characteristics, eventually obtained the highest yield. However the anti-aging physiological characteristics and yield of KB02F2 declined somewhat, there were still stronger than E-anti-Cotton 13 and parents.