【Objective】This study clarifies how different competition relationships affect leaf functional traits in Phyllostachys prominens, and examines the variation and interdependence of leaf morphology, pigment content, and non-structural carbohydrates (NSCs), providing a scientific basis for mixed-forest management and bamboo stand cultivation.【Method】We examined three stand types: P. prominens-P. edulis mixed forest (PM), P. prominens-broadleaf-conifer mixed forest (PB), and pure P. prominens forest (PP). Leaf morphological traits, pigment content, and NSCs accumulation characteristics were analyzed under different competitive conditions. Principal component analysis and partial least squares structural equation modeling (PLS-SEM) were employed to explore the differential impacts of interspecific and intraspecific competition on growth strategies and adaptive mechanisms.【Result】The PM stand significantly promoted leaf expansion and biomass accumulation in P. prominens, resulting in greater leaf length, width, area, dry mass, and specific leaf area compared to the PP and PB stands (P< 0.05), whereas leaf thickness and dry matter content were significantly lower. Chlorophyll a, chlorophyll b, and total chlorophyll contents were significantly higher in the PM stand than those in the PP and PB stands (P< 0.05), while the PP stand exhibited a significantly higher chlorophyll a/b. Soluble sugar content and soluble sugar-to-starch mass ratio were significantly higher in the PM and PP stands than those in the PB stand (P< 0.05). Principal component analysis and partial least squares structural equation modeling indicated that different competition relationships influenced bamboo growth characteristics, which in turn regulated leaf morphology and significantly affected pigment synthesis and NSCs accumulation (P< 0.001). Notably, bamboo height was strongly positively correlated with leaf morphological traits, which in turn, exhibited significant positive effects on pigment contents and NSCs.【Conclusion】P. prominens adapts to competitive environments by modifying its leaf morphology and physiological traits. It employs a resource acquisition strategy to enhance growth, promoting leaf expansion and sugar accumulation when competing with P. edulis, while optimizing carbon allocation to improve stress tolerance and resource use efficiency in broadleaf-conifer forests and pure stands.