Abstract: By studying the photosynthetic characteristics of hybrid variety flowering chinese cabbage sutai 1 in the field and understand the physiological basis for high yield, providing data support for environmental regulation on production, as well as improve the photosynthetic characteristics and photosynthetic traits heterosis of flowering chinese cabbage, provides a case study. Youlv 501 caixin, whose inbred lines is the male parent of Suetai 1, was used as the control, to determine the photosynthetic indicators of two varieties in different growth period, and daily changes in bud bolting stage. The experimental results showed that: (1) compare with control, sutai 1 displayed no difference on net photosynthetic rate under low light intensity in whole growth period, and displayed obvious higher than control under high light intensity. Moreover, sutai 1 appeared the photoinhibition phenomenon only in fruiting period, and was later than control. The control group appeared the photoinhibition phenomenon in all the stage except for collection period. The trend about both of the photosynthetic capacity of sutai1 and control leaves were exhibited this sequence from high to low: squaring and bolting stage, picking stage, flowering stage, seedling stage and fruiting stage. Moreover, the phenomenon that photosynthetic capacity of sutai1 leaves stronger than control became more obvious with later development progress. (2) the photosynthetic simulation parameters of sutai 1 in whole growth period: the range of light compensation point with sutai 1 was 14.31～40.57μmol?m-2?s-1, and the average was 24.18μmol?m-2?s-1, which lead to 7.38% reduction in value compared with control; the range of respiratory rate was 0.60～1.03μmol?m-2?s-1, and the average was 0.69μmol?m-2?s-1, which lead to 5.98% reduction in value compared with control; the range of apparent quantum yield was 0.0263～0.0323μmolCO2?μmol-1?photons-1, and the average was 0.0287μmolCO2?μmol-1?photons-1, which lead to 10.64% increment in value compared with control; the range of light saturation point was 1521.79～2008.53μmol?m-2?s-1, and the average was 1776.61μmol?m-2?s-1, which lead to 8.36% increment in value compared with control; the range of maximum net photosynthetic rate was 17.33～25.72μmol?m-2?s-1, and the average was 21.51μmol?m-2?s-1, which lead to17.51% increment in value compared with control. (3) In the bud bolting stage, the daily variation of net photosynthetic rate of sutai 1 displayed unimodal curve, and the maximum net photosynthetic rate was 27.30μmolCO2?m-2?s-1 at 10:00, and lead to 7.79% increment in value compared with control; light intensity was more than 800μmol?m-2?s-1 during 8:00~15:00 period, and the net photosynthetic rate was higher than control; the net photosynthetic rate displayed no difference with control when light intensity was less than 500μmol?m-2?s-1 during 16:00~17:00 period; the maximum net photosynthetic rate of sutai 1 decreased 13.37% when the temperature was above 35℃ during 12:00~14:00 period, but remained 23.65μmolCO2?m-2?s-1 high, and the maximum net photosynthetic rate of control decrease 17.43% at the same time. The experimental results showed that the photosynthetic capacity of sutai 1 was stronger in whole growth period, especially in key period of forming commodity (squaring and bolting stage), and can still keep higher net photosynthetic rate in high temperature and intensive light, possessing the photosynthetic physiological basis of high yield.