Abstract:The diurnal courses of the net photosynthesis(Pn)of the main tree species in the evergreen broad-leaved forest dominated by Quercus glauca under clear day in spring and summer showed significant midday decrease. The net photosynthesis of the evergreen species was the highest in autumn and the lowest when the plants were in the period of concentrate change of leaves. They still had Pn in winter. The photosynthetic rate of summer-green species was the highest in autumn too, but it began to defoliation in the end of October, when the environment was still suitable for photosynthesis. That caused the summed lower Pn in the year of summer-green species compared with the evergreen species, and their status would decrease in the development of the community. Between the two evergreen species, Quercus glauca can use the weaker light, that would ensure the dense crown having a higher Pn and keeping its dominated status in the community. Lithocarpus glaber Preferred to use stronger light. Their fewer leaves and the relative sparse crown could meet the require for light so as to get high photosynthesis and keeping its status of subdominant species. The diurnal course of Pn of the shrub and herb species in the community were the single peak type. Two shrub species, Loropethalum chinense and Lindera aggregata required relatively high light. The pteridophyta Woodwaria japonica had stronger shade tolerance and higher Pn, so it would become the stable accompany species in the community.