Abstract:Through the experiment of drought training at different degrees in vegetative growth stage and levels of nitrogen in the soil, mechanisms of soybean yield and its components to drought stress and re-watering were studied, which will provide a theoretical basis for practice and exploration of soybean water-saving, yield-increasing and drought resisting mechanisms. The intensity of water stress, time and nitrogen nutrition have a clear effect on the compensation effect of soybean yield and its components. Water stress could inhibit the increase of soybean grains per plant, but improve the100-seed weight significantly; nitrogen nutrition could limit the increase of 100-seed weight in soybean, but significantly improve the numbers of grain per plant under certain water conditions, and with the increase of the degree of water stress, the increase extent of the grains per plant would be reduced accordingly. Although the threshold ranges of compensation effects of soybean yield components produced by the nitrogen nutrition and water stress were different, but they had a certain area of coupling. In the area (the water stress durations were about 14d, soil water contents were 50%-55% of field moisture capacity, nitrogen amount were 97.5-225 kg/hm2), the compensation effects on the grains per plant and 100-seed weight were considerable intensive, the synergy of the water stress and nitrogen nutrition made the economic yield of soybean increase significantly and the soybean yield showed the strong compensation effect. Nitrogen nutrition and moderate water stress can enhance the growth capacity of soybean plant through the different approaches, the compensatory growth mechanism of the soybean is more complicated after the coupling of the two, and ultimately presents that water stress and the nitrogen can make the 100-seed weight and the grains per plant increase respectively, the synergy of the two can significantly increase the economic yield of soybean.