Abstract: To explore guidelines for nitrogen fertilization, nitrogen deficiency degree should be measured and estimated sensitively. Changes of leaf photosynthesis activity and physiological indices of maize were analyzed in this study. The results show that contents of soluble protein and pigments of maize leaves are decreased obviously along with the decrease of nitrogen concentration in the culture solution, and as well as photosynthesis activity of maize leaves and whole plant fresh weight, While the ratios of root to shoot are increased. These results indicate that there are significant effects on maize growth and activity of maize leaves under nitrogen-deficiency. Results of chlorophyll fluorescence study show that Fv/Fm, Fm/Fo, Sm, ETo/CSo, RC/CSo of maize leaves under the nitrogen-deficiency treatments are significantly lower than control leaves, in which Sm is the most sensitive index. While there are not significant differences of ABS/CSo, TRo/CSo and DIo/CSo under nitrogen-deficiency treatments. The correlation of Sm and nitrogen relative concentration in the cultivated solution is similar to the kinetics of enzyme-catalyzed reactions. These results suggest that the chlorophyll fluorescence measurements can detect changes of photoshythesis activity of nitrogen-deficiency maize leaves, and can be used to estimate the degree of nitrogen deficiency.