Abstract: Abstract: Sprinkler uniformity has posed a great challenge to the crop yield and water use efficiency in an irrigation system. A sprinkler is required to evenly deliver the water over the canopy and ground during and after the irrigation, where the crop canopy covers the surface. This study aims to explore the effect of sprinkler uniformity on the spatial distribution of soil water content, growth condition, and crop yield below different irrigation systems. The redistribution of sprinkler water was also considered below the crop canopy. A field test was conducted at the sprinkler irrigation experimental field of the Jiangsu University in Jintan District, Changzhou City, Jiangsu Province, in China (31。45′N, 119。17′E). Three treatments of irrigation (full irrigation, 2/3, and 1/3 water demand) and two levels of sprinkler uniformity (high: 75%, low: 55%) were set, according to the water demand for the winter wheat. Specifically, the sprinkler uniformity was obtained to adjust the sprinkler operating pressure (150-300 kPa) or the number of sprinklers simultaneously within each treatment (2-4). The irrigation volume was also evaluated, as the irrigation time changed. The distribution of sprinkler water was measured by the rain cans above and below the canopy, and a homemade stem-flow collector. Some parameters were also monitored, including the spatial distribution of soil water content, the growth and yield of winter wheat after sprinkler irrigation. The results showed that the interplant throughfall, stemflow, and below-canopy sprinkler losses (resulting from the redistribution of sprinkler water through the canopy) were ranged from 56.0%-73.9%, 25.0%-37.0%, and 2.5%-12.7% of the water above the canopy, respectively. There was a linear correlation (P<0.01) between the amount of water above and below the canopy in three sprinkler irrigations during the growing period. There was no significant change in the total amount of water below the canopy, due to the penetration and stalk flow in the canopy during the pulling-maturity period of winter wheat. The sprinkler irrigation performed uniformly higher above the canopy than that below by about 1.5%. The rates of below-canopy throughfall and stemflow depended on the canopy characteristics (Leaf Area Index (LAI), and plant height). The throughfall rate tended to decrease, as the LAI increased (or the plant height decreased), whereas, the stemflow rate varied in the opposite, indicating less influence from the sprinkler uniformity and irrigation volume. The coefficient of variation of the stemflow rate (49%-61%) was also higher than that of the throughfall rate (about 30%). Furthermore, the Content Uniformity (CU) of soil water was dependent on the initial Soil Water Content (SWC) before the sprinkler irrigation, whereas, less affected by the sprinkler uniformity after the sprinkler irrigation. The CU was still maintained at about 90% after the sprinkler irrigation, even if the sprinkler uniformity was reduced to 51%. But the low uniformity of sprinkler resulted in the SWC below the lower limit of crop irrigation (65% of field water holding capacity) at some locations within the sprinkler area, where the water stress triggered a small yield reduction. The yield differences were mainly presented in the spike number and thousand-grain quality. Consequently, there was a decreasing trend in the yield, whereas, an increasing trend in the yield coefficient of variation for the winter wheat, with the decrease of sprinkler uniformity and irrigation water volume. But there was a dominant effect of irrigation water volume on the yield. This finding can provide a theoretical basis to design sprinkler irrigation for the winter wheat.