【Objective】To investigate the response of C, N, P, and K distribution law in Xanthoceras sorbifolia seedlings to water and nitrogen addition, providing references for water-nitrogen environmental adaptation strategies and high-quality seedling cultivation.【Methods】A two-factor (nitrogen and water) randomized block design was adopted in this study. four N fertilization levels [N0: g/(m2·a), N1: 5 g/(m2·a),N2:10 g/(m2·a) and N3:15 g/(m2·a)] and three levels of water addition [ well watered (WCK), drought (Wd), and fully watered（Ww）] were set up to explore the impact on the ecological stoichiometric characteristics of Xanthoceras sorbifolia seedlings" leaves, branches, and roots.【Results】(1) The C, N, P, and K levels of seedlings were independently or interactively influenced by nitrogen and water, while the stoichiometric ratios were mainly affected by nitrogen addition. Under well-watered conditions (WCK), nitrogen addition increased C, N, and P levels. Under drought conditions (Wd), high nitrogen addition (N3) Ncould resist drought by increasing K level and decreasing N and P levels. Under well-watered conditions (Ww), only high nitrogen addition (N3) effectively alleviated nitrogen limitation. (2) C, N, P, and K nutrients were mainly concentrated in leaves, supporting photosynthesis and vegetative growth. The variability of N and P contents in leaves was high , but the N/P ratio remained stable.(3) The same element exhibited a high correlation between different organs, particularly between leaves and roots, contributing to the maintenance of stable growth.【Conclusion】Nitrogen addition can alleviate nitrogen deprivation whereas increases the demand for P and K. It is recommended to reduce nitrogen fertilizer application under suitable water conditions to reduce pollution and maintain growth potential.