Abstract: An experiment of foliage application of 0.3% MnSO₄ or 0.3% FeSO₄ solution to Shimenzaoshuo chestnut trees, three-year old, was conducted to explore effect of the foliage application on photosynthesis of the chestnut leaves. Photosynthetic indexes, such as chlorophyll content, photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO₂ concentration, water use efficiency (WUE) and stomatal limitation were measured between 10:00 am and 11:00 am with SPAD-502 chlorophyll meter and CIRAS-2 photosynthetic instrument on sunny days. Results show that the application of either of the solutions increased chlorophyll content, photosynthetic rate and WUE of the chestnut leaves and the application of FeSO₄ solution also improved stomatal conductance and transpiration rate of the trees. Analysis of the diurnal variation of photosynthetic indices reveals that the net photosynthetic rate of the leaves of young chestnut trees varied following a curve of parabolic shape with a peak appearing at 1:00pm. In CK, the stomatal conductance and the transpiration rate of the young chestnut leaves displayed a curve of “M” shape, while in the treatments of foliage application, they did a curve of parabolic shape, indicating that the foliage application of the solutions is conducive to enhancing photosynthetic capacity of the young chestnut tree leaves.