Chlorophyll contents and net photosynthetic rate (Pn) of leaves seated in different knots of the main stem of winged bean and the diurnal Photosynthetic Characteristics were determined in budding stage by LI-6400 portable photosynthesis system.The relationship between net photosynthetic rate (Pn) and its physio-ecological factors, including PAR,RH,Tl,GS,Ci and Tr, were clarified by regression analysis and correlation analysis. The results showed that Chlorophyll contents and Pn of leaves seated in different knots of winged bean were different, that was,with the knots increasing,the chlorophyll contents and Pn of the leaves declined. The diurnal change trend of Pn showed a double peak curve, presenting a typical phenomenon of “photosynthesis midday depression”. Among the ecological factors，Tl and RH were the key two ones that influenced the variations of Pn，and Tr was the major physiological factor that influenced the variations of Pn.