Estimating field crop evapotranspiration (ET_c) along with its components of soil evaporation and crop transpiration is crucial for developing effective agricultural water-saving strategies. This study separately estimated ET_c and its components in cotton fields using a SIMDualKc dual crop coefficient model. Data from a 2-year experiment (2010-2011) were used for model calibration and validation analysis. The experimental plots were irrigated at 1.00, 0.85, 0.70, 0.55, and 0.45 of full irrigation amount in north Xinjiang, China. Based on the results, SIMDualKc accurately estimated actual evapotranspiration (ET_{c adj}) and its components under deficit drip irrigation conditions. Cotton field transpiration accounted for 85.4-94.3% of the ET_c in the study area. Although plastic film significantly limited evaporative water loss, the fraction of water loss was still 5.7-14.6% of irrigation water. The adopted estimation method could lead to better understanding of where and when water loss occurs and how much water should be used for maximal benefit. A better understanding of these factors is critical for sustainable agricultural water management practices.