Abstract:In order to discuss the influence of different organic fertilizers substitute chemical fertilizer nitrogen on wheat yield and soil carbon and nitrogen components in winter wheat area of the Loess Plateau, provide theoretical basis for reducing the application of chemical nitrogen fertilizers, promote wheat quality and efficiency and sustainable agricultural green development in this area, the effects of different ratios of humic acid and organic fertilizers substitute chemical fertilizers on wheat yield and yield composition and soil carbon and nitrogen content were systematically studied. The experiment set up 7 experimental treatments in the winter wheat planting area of Shanxi Loess Plateau in 2019:100% chemical fertilizer N treatment (HF), 10% humic acid N+90% chemical fertilizer N (F1), 30% humic acid N+70% chemical fertilizer N (F3), 50% humic acid N+50% chemical fertilizer N (F5), 10% organic fertilizer N+90% chemical fertilizer N (Y1), 30% organic fertilizer N+70% chemical fertilizer N (Y3), 50% organic fertilizer N+50% chemical fertilizer N (Y5). The results showed that F3, F5, Y3, and Y5 treatments significantly improved 9.7%, 8.0%, 9.2% and 18.2% compared with HF, respectively. At the same time, Y5 significantly promoted the increase of the content of various active organic carbon and nitrogen components in the soil, and the increase range was between 36.8%~114.4% and 27.8%~105.4%; The content of soluble, water-soluble, microbial organic carbon, nitrogen and light organic carbon and nitrogen components under Y3 treatment was significantly increased by 21.1%~156.8% compared with HF. Compared with HF, the soluble, microbial, light organic carbon and the nitrogen content in the soil under F3 and F5 treatments were significantly increased by 25.4%~119.3%. At the same time, soluble organic carbon, microbial organic nitrogen, light group organic nitrogen had very significant positive correlations with grain yield. The soluble organic nitrogen could increase winter wheat yield by promoting the increase of ears per hectare. Total organic carbon, water-soluble organic carbon, and microbial organic nitrogen could increase yield by increasing the number of grains per spike. In conclusion, when 30%~50% organic fertilizer and humic acid were used for substitution of chemical fertilizer in winter wheat growing area of loess plateau, significant yield increase could be achieved, and the effects of active carbon and nitrogen components in soil could be improved. Among them, the 50% organic fertilizer replacement treatment has more significant effects on increasing yield and improving fertility, which is suitable for local promotion and application.