With attention to the development of pressurized irrigation systems and possibility of applying precise management of irrigation, especially in the localized irrigation system, it is necessary to irrigate the plant, exactly, according to the needs of it to achieve the highest water use efficiency. The purposes of this study were determination of actual water requirement and crop coefficients (Kc) of maize during the growth stages as a function of time and growing degree days, and determination of irrigation water use efficiency (IWUE) of maize under drip-tape irrigation system. This study was conducted in 2014 and 2015 at Agricultural Research Station of Isfahan University of Technology located in Lavark, Najafabad. Precision irrigation i.e. calculating the time and depth of irrigation water according to soil water balance in crop root zone were applied. Three different levels of nitrogen (N0, N150 and N300 kg/ha) under fertigation management in three replications were applied to maize. In first year the PR2 and in second year the tensiometer and weighting method were used in order to investigate soil water balance. The evapotrairation (ET) of reference crop using the FAO Penman-Monteith (FPM) equation and meteorological data were 759 and 742 mm in 2014 and 2015, respectively. Pan evaporation during the growing season were 891 and 826 mm in 2014 and 2015, respectively. The actual ET of silage maize (ET C ) by method of soil water balance were 584 and 570 mm for 2014 and 2015, respectively. The actual ET C for 2015, in grain harvest stage, were 649 mm. The amount of ET C in 90 days (silage harvest) was calculated by using FPM equation and crop coefficient (Kc-FAO) were 584 and 581 mm for 2014 and 2015, respectively. The results showed that ET was calculated using the Kc-FAO method was overestimated 10% higher than the actual ET C (120 days) in this study area. The average Kc measured in two years based on soil water balance, for maize SC 704 variety with a growing period of 90 days, were 0.49, 0.93, 1.12 and 0.82 in the initial, development, middle and final stages, respectively. The maximum daily Kc with drip-tape irrigation system was 1.13. Maximum leaf area index was 5 that observed at 68 days after planting. The highest yield (9370 kg/ha) and IWUE of seed (1.29 kg/m 3 ) were obtained in treatments with 150 kg nitrogen per hectare. Keywords : Maize, Irrigation Requirement, Crop Coefficient, Drip-Tape, Soil Water Balance