Abstract:Effects of nitrogen and phosphorus nutrition on gas exchange of maize (Zea Mays) were studied under soil drought conditions. The results show that nitrogen and phosphorus nutrition increase stomatal conductance of maize, but the role of nitrogen nutrition is bigger than that of phosphorus nutrition. Under drought conditions, nitrogen and phosphorus nutrition increased photosynthesis rate of maize, but the reason to raise photosynthesis rate is difference, nitrogen nutrition decreased stomatal and non-stomatal limits of photosynthesis simultaneously, but phosphorus nutrition mainly decreased non-stomatal limits of photosynthesis. So the role of phosphorus nutrition is bigger than that of nitrogen nutrition in raising water use efficiency of maize under drought condition.