Bamboo is a typical natural fiber reinforced composite material with superior mechanical strength and toughness. As a typical hierarchical material, the macroscopic properties of bamboo are determined by its microscopic structure. The vascular bundles are the reinforce phase in bamboo composite. There was little research on the variation of mechanical properties of bamboo vascular bundles. In this work, the mechanical properties of Moso vascular bundles along the axial direction were investigated by tensile test. It is shown that the longitudinal Young’s modulus and strength of the Moso vascular bundles are linearly increased from inner zone to outer surface.