Abstract: The photosynthetic characteristics of leaves from normal and chlorotic shiranuhi under field conditions were investigated using the CI-340 portable photosynthesis system, and the leaf epidermis features of them were observed by scanning electron microscope (SEM), the main results were showed that chlorotic leaf chlorophyll a+b concentration and leaf area were significantly lower than those of normal shiranuhi (p=0.045, p=0.003), whereas carotenoid concentration was dramatically higher in chlorotic leaves than in normal leaves from shiranuhi (p=0.049), stomas were all distributed in lower epidermis of both, at a.m. 8:00, no distinct differences were detected on the stomatal frequency and apertures among them. The single peaks were found on the diurnal variations in net photosynthetic rate (Pn) of them, the peak of normal shiranuhi occurred at 8:00, in advance two hours compared with that of chlorotic shiranuhi, furthermore, the peak of Pn was relatively lower in leaves from chlorotic shiranuhi than from the normal one. Simple correlation analyses showed that the factors affecting Pn of chlorotic shranuhi could be ranked, from the highest to the lowest, as stomatal conductance(Gs)> CO2 concentration in field (Ca) >photosynthesis availability radiation(PAR)> transpiration rate(Tr), however, Pn of normal shranuhi was significantly correlated to Gs and Tr.