Aims <p>Nitrogen deposition has a dual impact on plant growth, development, and adaptation to the environment. When subjected to simulated nitrogen deposition, dioecious plants display morphological and physiological sexual dimorphism. This study provides conclusive evidence for selecting suitable sex of dioecious plant species that used for reforestation in natural habitats with elevated atmospheric nitrogen deposition.</p> Methods <p>We conducted experiments under the background of simulating nitrogen deposition and mainly analyzed through metabolomics and transcriptomics methods.</p> Results <p>Female <i>Populus deltoides</i> exhibited higher leaf nitrogen content, increased leaf chlorophyll levels, and enhanced photosynthetic capacity, resulting in significantly superior growth performance compared to male <i>P. deltoides</i>. Metabolome analysis revealed that the metabolites enriched in female poplar leaves were quantitative and qualitatively higher than male leaves following simulated nitrogen deposition, particularly enriched in various nitrogenous compounds, in comparison to male <i>P. deltoides</i>. Transcriptome analysis revealed that female <i>P. deltoides</i> were capable of enhancing their own growth and development under nitrogen addition conditions by activating specific KEGG pathways, such as phenylpropanoid biosynthesis, phytohormone signaling, and nitrogen metabolism. The addition of nitrogen led to the up-regulation of genes associated with nitrogen uptake and transformation, and the establishment of a complex gene regulatory network involving multiple core transcription factors in female <i>P. deltoides</i>, as opposed to males.</p> Conclusions <p>Simulated nitrogen deposition confer a more favorable reaction in female <i>P. deltoides</i> compared to males, shedding light on the mechanisms underlying sex-specific responses of dioecious plants in the context of increased atmospheric nitrogen deposition.</p> Graphical Abstract <p></p>