【Objective】Bambusa multiplex has sympodial tufted rhizomes and is widely distributed in subtropical bamboo regions of China, with good adaptability and cold tolerance. Analyzing the morphological characteristics of its fiber growth provides a basis for the rational utilization and in-depth study of bamboo fiber resources.【Method】Using shoots and culms of B. multiplex as materials, fiber traits were detected by a fiber analyzer after fiber separation by the Franklin method, and the relationship between internodal length and fiber traits was analyzed by One-way analysis of variance (ANOVA) and Pearson’s correlation (PCR).【Result】Fiber traits in the 2nd to 4th internodes of B. multiplex shoots showed no significant differences, making them suitable test materials for fiber growth research. Under different growth lengths of the 2nd to 4th internodes in shoots, three traits—fiber length, ratio of fiber length to width and kink rate—exhibited normal distributions. Bamboo shoots fiber length (y₁) and ratio of fiber length to width (y₂) were extremely significantly positively correlated with shoot internode length (x₁), respectively. Their regression equations with internode length were: y₁ = 0.347 ln x₁ + 0.622, y₂ = 0.004 x₁³- 0.282 x₁² +8.773 6 x₁ + 23.601.In culms, five traits—internode length, fiber length, fiber width, ratio of fiber length to width, and kink angle—showed extremely significant differences among the 1st to 13th internodes. The first four traits increased and then decreased with increasing internode number, while the last trait showed a fluctuating upward trend. Internode length, fiber length, and ratio of fiber length to width reached their maximum values at the 6th internode, measuring (46.35±6.44) cm, (2.55±0.05) mm, and 174.81±4.40, respectively. Fiber length and ratio of fiber length to width in the 2nd internode [(2.31±0.07) mm and (161.38±4.39)] were closest to the whole-culm averages [(2.31±0.03) mm and (161.18±0.06)].In culms, three traits—fiber length, kink index, and kink rate—showed normal distributions. Bamboo culms fiber length (y₃) was extremely significantly positively correlated with culm internode length(x₂), described by the regression equation: y₃= 0.857 x₂^0.28. Traits such as whole-culm fiber length were not strongly correlated with culm age. For one-four-year-old B. multiplex culms, the average whole-culm fiber length, fiber width, ratio of fiber length to width, mean curl degree, kink index, kink rate, kink angle, and fine fiber index were (2.31±0.03) mm, (14.34±0.05) μm, 161.18±0.06, (4.13±0.11)%, (200.30±4.97)%, (275.78±6.53)%, (24.95±0.05)°, and (86.85±0.38)%, respectively.【Conclusion】The stable fiber traits in the 2nd to 4th internodes of B. multiplex shoots make them suitable for future research. The correlation between fiber traits and internode length aids in exploring the mechanisms of fiber development in bamboo shoots. Significant differences in fiber traits among culm internodes reflect the dynamic process of fiber development. The significant positive correlation between fiber length and internode length, along with the weak correlation between whole-culm fiber traits and culm age, indicate that bamboo fiber growth follows unique laws influenced by multiple factors.