Abstract: In order to explore the regulating effects of nano materils on the the growth and development of bamboos, we measured the effects of different concentrations of nano SiO₂(150,300,450 mg/L)on Indocalamus barbatus McClure by foliar spraying. The results showed that compared to control, all treatments of different concentrations of nano SiO₂ could increase the gas exchange parameters and chlorophyll fluorescence parameters to some extent during the experiment, such as net photosynthetic rate, transpiration rate, stomatal conductance, PSⅡ potential activity, effective photochemical efficiency, actual photochemical efficiency, electron transport rate and photochemical quench, the optimal concentration of nano-SiO₂ was 300 mg/L. Compared to control, the above parameters significantly(p<0.05)increased 23.6%,34.9%,20.4%,8.8%,7.9%,26.6%,34.1% and 19.3% respectively after 21 days, but the intercellular CO₂ concentrations and PSⅡ maximal photochemical efficiency were not obviously(p>0.05)changed, and the non-photochemical quench was inhibited in the late experiment period. All above results indicated that exogenous nano SiO₂ treatment could effectively improve the stomatal conductance of In. barbatus McClure, promote the leaves( function on the absorption, transmission and transformation of light energy, increase the opening degree of PSⅡ reaction centers, reduce the antenna dissipation, improve actual photochemical efficiency and electron transport rate of PSⅡ, and then to improve net photosynthetic capacity of In. barbatus McClure. The improvement of photosynthetic activity of mesophyll cells may be the major factor of nano SiO₂ to promote the photosynthetic capacity of In. barbatus McClure.