Abstract: 【Objective】To determine the optimum nitrogen application rate for soybean intercropping with double-plant maize in one hole in Hetao irrigation area.【Methods】Two rows of maize and three rows of soybean were intercropped. The width was 2.2 m,the spacing between maize and soybean was 60 cm. Maize planted by double-plant in one hole and soybean planted by one grain in one hole. Based on 420 kg/hm²（CK） of single nitrogen fertilizer for double-plant maize in one hole,the treatments with 10%,20%,30% and 40% reduction of nitrogen fertilizer were set up to compare and analyze the maize yield,soybean yield,maize agronomic traits and other indicators among the treatments,and calculate the input-output and efficiency.【Results】The yield results show that,under the intercropping pattern of double-plant maize in one hole and soybean in Hetao irrigation area,the highest yield of maize was 13 578.2 kg/hm² under the treatment with 10% reduction of nitrogen fertilizer;the highest yield of soybean was 1 094.3 kg/hm² under the treatment with 40% reduction of nitrogen fertilizer;the optimum nitrogen application rate for high yield of maize is 0-20% reduction of nitrogen fertilizer. Compared with CK,the benefit results showed that the treatment with 20% reduction of nitrogen fertilizer had the highest benefit,with an increase of 414.40 yuan/hm²,followed by the 10% reduction of nitrogen fertilizer,but the treatment with 30% and 40% reduction of nitrogen fertilizer was poor benefit.【Conclusion】Comprehensive yield and benefit showed that the optimum nitrogen application rate was 336 kg/hm²,20% reduction of nitrogen fertilizer for soybean intercropping with double-plant maize in one hole planting pattern in Hetao irrigation area.

Key words: Maize, Double-plant in one hole, Soybean, Intercropping, Nitrogen application rate