[Aim]  To investigate the occurrence of the brown planthopper (Nilaparvata lugens) on rice plants under different soil nitrogen treatments, and to compare the physiological defenses of rice (including nutrients, defense signal substances and defense enzymes) under different soil nitrogen treatments in response to feeding by brown planthoppers. [Methods]  Brown planthopper populations were investigated in fields with four different soil nitrogen treatments: High (270 kg/hm²), medium (180 kg/hm²), low (90 kg/hm²) and no-nitrogen (0 kg/hm²). Rice seedlings were cultivated in the laboratory, and their jasmonic (JA) and salicylic acid (SA) contents after they had been fed on by brown planthoppers were compared under three nitrogen concentrations: high (3 mmol·L^﹣1 KNO₃), low (1 mmol·L^﹣1 KNO₃), and no-nitrogen (0 mmol·L^﹣1 KNO₃). An enzyme-labeled instrument was used to detect the amino acid (AA) and sugar (SS) content of rice plants, as well as their catalase (CAT), superoxide dismutase (SOD), polyphenol oxidase (PPO) and peroxidase (POD) activity. [Results]  In 2022, during the rice booting stage, the population sizes of brown planthoppers in the high, medium, and low, nitrogen treatment fields were 712, 650, and 548 individuals per 100 clumps, respectively, all of which were significantly higher than that in the no-nitrogen treatment (P < 0.05). During the grain filling stage, population sizes under the high and medium nitrogen treatments were 782 and 767 individuals per 100 clumps, respectively, which were significantly higher than those under the low and no-nitrogen treatments (P < 0.05). In 2023, during both the booting and grain filling stages, the population sizes of brown planthoppers under the high and medium nitrogen treatments were significantly higher than those under the low and no-nitrogen treatments (P < 0.05). After brown planthoppers were allowed to feed on rice cultivated under no-nitrogen, low-nitrogen, and high-nitrogen soil conditions, the AA content of rice increased by 48.5%, 20.3%, and 27.3%, respectively, with significant changes observed under the no-nitrogen and low-nitrogen treatments (P < 0.05). The SS content of rice decreased significantly under all nitrogen treatments (P < 0.05), with reductions of 29.6%, 23.5%, and 17.1%, respectively. The JA content of rice increased by 31.6%, 23.2%, and 9.8%, respectively, whereas the SA content increased by 20.6%, 27.5%, and 55.0%, respectively, under each nitrogen treatment. Under the no-nitrogen and low-nitrogen treatments, the CAT content of rice increased by 5.01% and 4.02%, respectively, after feeding by brown planthoppers, whereas the CAT content decreased by 1.05% under the high-nitrogen treatment. The PPO content of rice increased by 25.94% and 25.08% under the no-nitrogen and low-nitrogen treatments, respectively, but decreased by 0.03% under the high-nitrogen treatment. The SOD content of rice increased by 15.41%, 10.54%, and 42.09%, respectively, and the POD content increased by 125.33%, 89.55%, and 55.95%, respectively, under each nitrogen treatment. [Conclusion]  Increased soil nitrogen exacerbates the stress on rice plants caused by brown planthopper feeding activity. Brown planthopper feeding activity elicited different physiological responses from rice plants under different soil nitrogen treatments. Low soil nitrogen levels were more conducive to enhancing the defensive responses of rice plants to attack by the brown planthopper.