Abstract: The index of ecophotosynthetic characteristics and the chlorophyll contents of the two varieties of pecan (Elliott and James) were measured by the Li6400 portable photosynthetic system in late August．The results showed that:(1) the net photosynthetic rate and transpiration rate of the two varieties was in bimodal curve，but the volum and the peak time were different．(2) The net photosynthetic rate of these two varieties had negative correlation with photosynthetic active radiation，intercellular CO2 concentration，air temperature and other factors，but significantly positively correlated with the stomatal conductance, indicate that stomatal conductance is the dominant factor affect photosynthetic rate．(3) Comparison of chlorophyll contents and light response curve parameters found that： contents of chlorophyll a,b of James was greater than those of Elliott，but the chlorophyll contents a/b was less； varieties of light compensation point of James was lower than that of Elliott，but the maximum net photosynthetic rate and the view of the quantum efficiency of James were higher than those of Elliott, which indicated that the James had stronger shade tolerance，larger range of light adaptation，and might be better adapted to the ecological environment in Northern Anhui．