Abstract: 【Objective】 Nitrogen application and planting density are two important technical measures affecting crop growth and increasing yield. The study on cultivation mode of tartary buckwheat under the interaction of nitrogen application and planting density can provide a theoretical basis for high-yield and efficient planting of tartary buckwheat in cool areas of the loess plateau. 【Methods】 The effects of nitrogen application amount （75,120 kg/hm² pure nitrogen） and planting density （0.6,0.9,1.2 million plants/hm²） on phenological stage,plant height,branch number of main stem,lodging rate,soil water utilization rate,and yield of tartary buckwheat were analyzed by a two-factor test. 【Results】 Six treatments had little effect on the growth period of Heifeng No. 1. Combined with the two factors,the combination of plant height,number of main stem branches and lodging rate with the application of pure nitrogen 120 kg/hm² and the planting density of 1.2 million plants/hm² performed better. Among them,the plant height was 116.87 cm,the number of main stem branches was 13.6,and the lodging rate was 1.74%. At the two nitrogen fertilizer levels,the soil water efficiency and yield were shown as planting density of 1.2 million plants/hm²>0.9 million plants/hm²>0.6 million plants/hm²,and under the interaction treatment,the combination of pure nitrogen application of 120 kg/hm² and planting density of 1.2 million plants/hm² was the best. Among them,the soil water utilization rate was 2.70 kg/（hm²·mm） and the yield was 1 504.08 kg/hm². 【Conclusion】 Under the condition of interaction between nitrogen application amount and density,with the combination of pure nitrogen application of 120 kg/hm² and planting density of 1.2 million plants/hm²,the indexes of tartar-buckwheat Heifeng No.1 performed well and had the highest yield,which can be used as a reference for the cultivation mode of high yield and high efficiency.

Key words: Tartary buckwheat, Nitrogen application, Planting density, Yield