Abstract: In order to optimize the nitrogen fertilizer application scheme for cauliflower, realize the reduction and efficiency increase of chemical fertilizer, and improve the economic benefits of planting, a field experiment was carried out in Jiangtian Town, Changle District, Fuzhou City. In this study, broccoli cultivar ‘Changsheng 65 days’ was used as the experimental material, and four treatments were set up: nitrogen-free group (control, N₀PK), 70% optimized nitrogen group (N₁PK), optimized nitrogen zone (N₂PK) (converted to pure N 240 kg·hm⁻²), and 130% optimized nitrogen group (N₃PK). Each treatment was applied with the same amount of phosphorus fertilizer (P₂O₅ 75 kg·hm⁻²) and potassium fertilizer (K₂O 265.2 kg·hm⁻²) according to the recommended values of local production conditions. The effects of different nitrogen treatments on the agronomic traits, yield, quality indicators and economic benefits of cauliflower were analyzed. The results showed that: under the condition of applying the same amount of phosphorus and potassium fertilizer, the single head weight of cauliflower treated with the optimized nitrogen application (N₂PK) reached 0.78 kg, and the yield reached 34200 kg·hm⁻², which was 32.87 % higher than that without nitrogen application (N₀PK). The quality of cauliflower was the most balanced, with the highest vitamin C content of 0.12 mg·g⁻¹ and the highest soluble sugar content of 43.97 mg·g⁻¹, while the nitrate residue was only 0.31 mg·kg⁻¹, which was within the safe and controllable range. The net income of cauliflower planting reached 106798.06 yuan per hectare with an input-output ratio of 9.28, both of which were the maximum values across all treatments. In summary, for cauliflower production in Changle District, it was recommended to use the optimized nitrogen application (N₂PK) treatment as the best fertilization scheme. This scheme could take into account the efficient utilization of fertilizer and production income, and realize the synergistic improvement of agronomic traits, yield, quality and economic benefits of cauliflower.