Abstract: An experiment was conducted to study the effects of manganese fertilizer on maize photosynthetic response. The stomatal conductance(Cs), intercellar CO2 concentration(Ci), transpiration rate(Tr), and net photosynthetic rate(Pn) were measured and water use efficiency was calculated by following formula: WUE=Pn/Tr. The results showed that application of manganese fertilizer lessened the stomatal and non-stomatal limitation on maize photosynthesis performance. Manganese fertilizer made the Pn increase significantly compared with control treatment, especially in soil drought treatments. Under soil drought conditions, the Cs, Pn, and WUE increased by 58.11%, 42.07% and 50.00%, respectively, in manganese treatments. These results indicated that application of manganese fertilizer alleviated the inhibition of soil drought on maize photosynthesis.