In recent years, it is of great significance for urban ecological environment protection and civilization construction to study the remediation technology and principle of garden plants to reduce air pollutants and clarify the effect mechanism of nitrogen oxide pollution on plant physiology and ecology. In this paper, Bougainvillea spectabilis Willd seedlings were taken as the research object. We designed a short time high concentration of ¹⁵NO₂ stress treatment by artificial fumigation. Taking CK as control, the effects of 8.0 μL/L ¹⁵NO₂ treatment and 4.0 μL/L ¹⁵NO₂ treatment on ¹⁵N uptake and ¹⁵N-amino acid content in various organs of B. spectabilis were compared in order to summarize the dynamics and metabolism of nitrogen absorption and distribution in various organs of B. spectabilis under ¹⁵NO₂ stress. The results showed that ¹⁵NO₂ stress significantly increased the ¹⁵N-nitrogen content in all organs of B. spectabilis, and the leaf was the main accumulation organ of ¹⁵N-nitrogen. Compared with 4.0 μL/L and 0 μL/L. The contents of ¹⁵N and ¹⁵N-nitrate nitrogen in organs were significantly increased under 8.0 μL/L treatment. Compared with 4.0 μL/L ¹⁵NO₂ treatment, the contents of ¹⁵N-ammonium nitrogen were significantly increased except its content in leaves was significantly decreased by 54.0%. The distribution of nitrogen in different organs of B. spectabilis was significantly different, and the general trend was leaf>root>stems under 4.0 μL/L ¹⁵NO₂ treatment. With the increasing concentration of ¹⁵NO₂, the contents of ¹⁵N-amino acids in all organs of B. spectabilis under 4.0 μL/L ¹⁵NO₂ treatment showed an increasing trend, and the distribution rate was leaf>root>stems. Under the treatment of 8.0 μL/L, the contents of ¹⁵N-amino acids in all organs did not show a uniform trend of change, and the contents of some ¹⁵N-amino acids in all organs showed a downward trend compared with that of 4.0 μL/L. Therefore, after different concentrations of ¹⁵NO₂ stress, the absorption of ¹⁵N and the synthesis of ¹⁵N-amino acid in each organ of B. spectabilis varied. The absorption of ¹⁵N and the content of ¹⁵N-amino acid in each organ of B. spectabilis under 4.0 μL/L ¹⁵NO₂ stress showed an upward trend, and leaves were the main organs of ¹⁵N and ¹⁵N-amino acid accumulation. 8.0 μL/L ¹⁵NO₂ stress inhibited ¹⁵N allocation in roots and promoted ¹⁵N allocation in leaves and stems, with leaves being the main organ for ¹⁵N accumulation. These results provide a theoretical basis for the migraton and transformation of nitrogen oxide pollution in plants.