A hydroponic experiment was used to study the effects of poly-γ-glutamic acid addition on the growth of Chinese cabbage and its photosynthesis characteristics,such as net photosynthesis rate(Pn),stomatic conductance(Gs),intercellular CO2 concentration(Ci),and transpiration rate(Tr).The results shows that the level of Pn,Gs,Tr and Ci in Chinese cabbage leaf treated with poly-γ-glutamate acid increases compared with control when the concentration of nutrient decreases.The application of poly-γ-glutamate acid with 90% nutrient concentration significantly increased chlorophyll a in Chinese cabbage leaves.When the nutrient concentration was 70%-100%,the above ground yield of cabbage improved compared with control,meaning that poly-γ-glutamate acid can promote transformation of light,energy capture,increase the energy efficiency through reducing the stomatal limitation,increasing the chlorophyll content and the capacity of absorption of light intensity.