Gas exchange, chlorophyll a fluorescence kinetics and reflectance spectroscopy were investigated to explore photosynthetic characteristics and photoinhibition in Iris L. seedling leaves. Leaf orientation had a great influence on the irradiance interception of leaves under natural conditions. Net photosynthetic rate (Pn) in Iris L. seedling leaves was linearly correlated with photosynthetic active radiation (PAR). Leaves grown with east-west orientation had a higher Pn than that in leaves grown with south-north orientation. Compared with the east-west grown leaves, the leaves grown with south-north orientation contained relatively higher chlorophyll content (Chl) and carotenoid content (Car). During daily courses, no serious photoinhibition was induced in leaves with all orientations. Interestingly，the south-north grown leaves showed a more noticeable incline than the east-west grown leaves. In addition, photochemical reflectance index (PRI) in leaves grown with east and south orientation were significantly down regulated; changes of PRI (△PRI) ranked in the order of east > south > west > north. Thus, we deduced that the co-operation of leaf orientation and the incline of leaves reduce the irradiance interception of leaves in field; the down-regulation of the efficiency of light energy utilization and the strengthening of xanthophyll cycle might alleviate the photoinhibion in Iris L. leaves.