Abstract: 【Objective】 To study the effects of different nitrogen application on growth and soil nitrogen balance of processed tomato. 【Methods】 Based on the critical nitrogen concentration model, four treatments, no nitrogen (N₀), 200 kg/hm² (N₁), 300 kg/hm² (N₂) and 400 kg/hm² (N₃), were used to study the effects of different nitrogen application rates on the growth of processing tomato and the transport and balance of soil nitrogen. 【Results】 The results showed that: (1) in the seedling stage, there was no significant difference in the growth of processing tomato between the treatments; after fruit setting stage, N₂ treatment could effectively promote the growth of processing tomato compared with other treatments. In 2018, the plant height of processing tomato under N₂ treatment in red ripening stage was 85.5 cm, significantly higher than th of other treatments. In the same period, the stem diameter under N₂ treatment was 18.40 mm, significantly higher than that under N₀ treatment, but there was no significant difference with other nitrogen treatment, and the same trend was observed in 2019. (2) The soil nitrate nitrogen of each treatment mainly distributed in 20-40 cm soil layer, and the content of nitrate nitrogen in each soil layer with the increase of nitrogen application amount; in 2018, the nitrate nitrogen content of N₃ treatment in seedling pulling period mainly remained in the soil layer below 40 cm, accounting for 54.72% of the total nitrate nitrogen content, and there the same trend in 2019, with a high risk of leaching; the distribution of soil nitrate nitrogen under N₂ treatment relatively balanced, which effectively reduce the residual nitrogen in the soil and improve the utilization rate of nitrogen. (3) The surplus of nitrate nitrogen in the soil profile increased with the increase of nitrogen application amount; the nitrogen in N₀, N₁ and N₂ treatment mainly brought out of the soil by the way of crop absorption, and the nitrogen in N₃ treatment was mainly left in the soil; N₁ treatment could reduce the residual amount of nitrogen in the soil, but also reduce the utilization rate of nitrogen. N₂ treatment was conducive to improving the apparent utilization rate of nitrogen and reducing the nitrogen surface N₃ treatment promoted the absorption of nitrogen, but increased the residue of nitrogen in the soil and reduced the nitrogen utilization rate. 【Conclusion】 Under the nitrogen operation plan based on the critical nitrogen concentration model of processing tomato, during the seedling stage of processing tomato, 44 kg/hm² nitrogen reduction and fertilization can be applied according to N₁ treatment in production. After the flowering stage, 234 kg/hm² nitrogen operation plan can promote plant growth, and the nitrogen residue in soil is relatively small, which ensures high nitrogen utilization rate and economic benefit.