Abstract: The leaf area index (LAI) and leaf biomass was studied in the growing period of maize which variety was‘Qingnong 8’in order to investigate the effect of water-fertilizer coupling on the growth of maize. The results showed that the LAI was significantly affected by water-fertilizer coupling, and irrigation was the most important factor then was nitrogen fertilizer and potassium fertilizer. However, the LAI could decrease by more irrigation and fertilization. The LAI could increase 47.46% by irrigation in N2K2 treatments. Moreover, the highest increase in LAI was 37.75% by nitrogen fertilizer treatment, while the LAI increased 9.62% by potassium fertilizer in W2N2 treatments. There were positive correlations between the root characteristics and the weight of seed, leaf and stalk weight. The correlation coefficient of the weight of seed and root was 0.97. It was important for the theory and practice in improving the water-fertilizer utilization rate and reducing the waste of water resource by suitable water-fertilizer coupling management.