Application of drip-tape irrigation systems is highly important for managing water consumption and increasing of water use efficiency and nitrogen use efficiency in term of environmental and economic justifications. The purpose of this study was to investigate the interaction of water and nitrogen fertilizer on total biomass (TB), water use efficiency (WUE), irrigation water use efficiency (IWUE) of silage maize under drip-tape irrigation system. Four irrigation levels, including two deficit irrigation levels (W1=0.86ETc, W2=0.93ETc), a full irrigation level (W3=ETc), and an over irrigation level (W4=1.06ETc) and three nitrogen fertilizer levels, including no nitrogen fertilizer (N0), 150 kg N ha -1 (N150), and 200 kg N ha -1 (N200) were considered. The twelve experimental treatments arranged in a strip-plot design with complete randomized blocks with three replicates. The statistical analysis was performed using SAS software. The studied indices were stem height and diameter, leaf area index, and total biomass during growth period. Irrigation management was performed, based on the calculation of maize evapotrairation by using FAO-Penman Monteith (FPM) equation and soil moisture measurement in the root depth before each irrigation. The result showed that there were a significant effect of irrigation on total biomass and IWUE (P 0.05). There were a significant effect of nitrogen on TB and WUE (P 0.01). The minimum TB obtained for W1N0 treatment, 14537 kg/ha, and the maximum TB obtained for W4N200 treatment, 27893 kg/ha. The minimum WUE for total biomass was 3.09 kg/m 3 for W2 level and maximum was 3.57 kg/m 3 for W4 level. Overall, TB and IWUE increased with increasing nitrogen. The applied water depth was 585, 633, 678, and 719 mm for W1, W2, W3, and W4 levels, respectively. Comparison of the results of this study with similar studies under sprinkler irrigation system showed that, applied water for drip-tape irrigation system was 20.5% lower and total biomass was 20.2% higher than sprinkler irrigation system. Also maize evapotrairation and total biomass for drip-tape irrigation system were 12.17% (58.75 mm) and 20.27% (3312.7) higher than sprinkler irrigation system, respectively. The WUE and IWUE of TB of silage maize in drip-tape irrigation system were 1.05 and 1.73 times higher than sprinkle irrigation system. In general, the results showed that drip-tape irrigation system through increasing irrigation efficiency and decrease of soil surface evaporation would save water consumption and increase the water use efficiency and yield production. Keywords : Deficit irrigation, Sprinkle irrigation, Evaporation loss, Water use efficiency, Fertigation