Abstract: The replacement of chemical fertilizers by organic fertilizers is an important technical measure to achieve fertilizer reduction and efficiency, and control soil pollution. The study investigated the responses of maize yield, nitrogen uptake and use efficiency, and soil nitrogen leaching to different proportions of organic fertilizers replacing chemical fertilizers, and to provide a scientific basis for the efficient use of maize nitrogen resources and the prevention and control of agricultural non-point source pollution in the Yellow River Water Irrigation Area of Ningxia. A field experiment was conducted at the National Meteorological Station of Yongning County, Ningxia from 2022 to 2023. A completely randomized block experimental design was adopted based on the local conventional nitrogen application rate of 270 kg·hm^-2. The fertilization treatments was as follows: 100% chemical fertilizer (T1), 2/3 chemical fertilizer + 1/3 organic fertilizer (T2), 1/3 chemical fertilizer + 2/3 organic fertilizer (T3), 100% organic fertilizer (T4) and control check (CK). The following variables were analysed: maize yield, nitrogen uptake, nitrogen transport and utilization efficiency, and soil nitrogen loss. The results showed that maize yield and above-ground nitrogen uptake by plants at maturity were the highest in the T2 treatment, with an average increase of 73.42% and 3.67% in yield and 97.09% and 9.98% in above-ground nitrogen uptake by plants at maturity over CK and T1 in 2 years of averaged experimental data, respectively. Secondly, maize nutrient organ nitrogen transport, nitrogen transport efficiency, nitrogen transport contribution to grain and post-flowering nitrogen assimilation were increased significantly by 171.18%, 19.67%, 36.89% and 72.17% on average values for 2 years in T2 treatment compared to CK and by 24.36%, 6.74%, 12.94% and 3.55% on average in T2 treatment compared to T1, respectively. Maize apparent nitrogen recycling rate, nitrogen recovery efficiency, nitrogen fertilizer efficiency and nitrogen assimilation were increased significantly by 73.42% and 3.67% respectively, in the T2 treatment for the 2 a average values compared to CK and T1, and the average amount of nitrogen absorbed increased by 97.09% and 9.98%. The mean values of apparent recycling rate, agronomic efficiency of N fertilizer and N fertilizer bias productivity were significantly higher by 22.58%, 9.17% and 3.67% respectively in the T2 treatment than T1 treatment. While there was no significant difference in the harvest index among treatments between 2 a. In addition, the total N, nitrate N and ammonium N concentrations in the leachate were relatively low in the T2 treatment. Compared with T1, the total nitrogen, nitrate nitrogen and ammonium nitrogen leaching and leaching coefficients in the T2 treatment were reduced by 24.56%, 25.29%, 23.70%, 37.95%, 39.44% and 26.83% for 2 a, respectively. Indicators of maize nitrogen nutrient uptake, translocation and utilization showed a significant positive correlation with yield. In the regression curve of yield versus organic fertilizer substitution ratio, at the highest point of yield corresponding to the organic fertilizer substitution ratio, maize had higher nitrogen uptake, transport and utilization efficiency and lower nitrogen leaching. Therefore, the optimal organic fertilizer substitution ratio for maize cultivation is 98.64 kg·hm^-2 (36.53% organic fertilizer substitution ratio for chemical fertilizer) in the Yellow River Water Irrigation Area of Ningxia, which can both achieve the efficient use of maize nitrogen resources and reduce agricultural nonpoint source pollution.