In the near and future climate change scenarios, agricultural meteorological disasters, such as drought, cold damage and high temperature, will occur frequently, which will seriously affect agricultural production yield. Oligosaccharides can improve crop stress resistance and protect crop growth. Alginate oligosaccharides (AOS) were prepared by enzymatic degradation of alginate extracted from brown algae. In order to study the growth promotion behavior of Alginate oligosaccharide on wheat (Triticum aestivum L.), 25 mg/L, 50 mg/L, 100mg/L aqueous solution of AOS were applied through foliar spraying at the greening stage, jointing stage and booting stage of wheat. The effects of different treatments on wheat yield and yield components were studied in Yongshou county dry farming experiment station of northwest A&F University located in the Weibei Arid Plateau of Shaanxi province. Foliar application of alginate oligosaccharides had a significant effect on the yield of tested three varieties. The effect of leaf spraying of alginate oligosaccharides on the yield of dryland wheat was greatly related to the spraying period, alginate oligosaccharide concentration and variety. The yield of wheat was significantly increased when wheat was treated with 25 mg/L and 50 mg/L, and the yield increase range was 3.21-17.51% on CH1and TM6 variety, but the yield of ZM 175 was not significantly affected．The yield of wheat was reduced when wheat was treated with 100 mg/L. Spraying 25 mg/L and 50 mg/L alginate oligosaccharide at the greening stage, jointing stage and heading stage of wheat increased the number of grains per spike and the 1000-grain weight of wheat. The spike number, the number of grains per spike and the 1000-grain weight of wheat were the main factors that formed wheat yield. Alginate oligosaccharides increased the levels of these three factors, thus increasing wheat yield.