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BACKGROUND: Early studies have confirmed that multi-scale hydroxyapatite/chitosan microtubules are excellent in osteogenesis. Angiogenesis is critical in the process of osteogenesis. It is significant to explore the role of tube structure with multi-scale microtubules in its vascularization and related mechanisms. OBJECTIVE: To explore the effect of multi-scale hydroxyapatite/chitosan microtubule structure on rabbit bone defect repair and vascularization. METHODS: Multi-scale hydroxyapatite/chitosan microtubule structure and hydroxyapatite/chitosan monomer structure were constructed and co-cultured with bone marrow mesenchymal stem cells for 21 days. The adsorption ability of the material to cells and the cell state were observed under the electron microscope. Bone defect models were made on the radius of 48 adult New Zealand white rabbits. Rabbits in the experimental group (n=24) were implanted with multi-scale hydroxyapatite/chitosan microtubule structure material. Rabbits in the control group (n=24) were implanted with hydroxyapatite/chitosan monomer structure material. Emission computed tomography, X-ray, histomorphological examination, and immunohistochemistry for CD31 and vascular endothelial growth factor protein detection were performed at 4, 8, and 12 weeks after surgery. The animal experiment was approved by the Ethics Committee of Jiangxi Provincial People’s Hospital. RESULTS AND CONCLUSION: (1) Under the electron microscope, the multi-scale hydroxyapatite/chitosan microtubule structure materials were interlinked and had a good spatial structure. The number of bone marrow mesenchymal stem cells on the multi-scale hydroxyapatite/chitosan microtubule structure material was more than that on the hydroxyapatite/chitosan monomer structure material. (2) Emission computed tomography exhibited that the blood pool image was higher in the experimental group than that in the control group at various time points after surgery (P < 0.05). (3) X-ray films showed that the formation of multi-scale microtubules was more obvious in the experimental group than that in the control group. (4) Hematoxylin-eosin staining demonstrated that at 12 weeks after surgery, the appearance of osteoblasts and angiogenesis was obvious in the experimental group; only a few regenerated blood vessels and osteoblast attachment were found at the fractured end in the control group. Immunohistochemistry for CD31 exhibited that the microvessel density of the experimental group was higher than that of the control group at each time point (P < 0.05). (5) Western blot assay results displayed that the expression of vascular endothelial growth factor protein in the experimental group was higher than that in the control group at each time point (P < 0.05). (6) The results showed that the multi-scale hydroxyapatite/chitosan microtubule structure had better osteogenesis and vascularization ability than its monomer structure. [ABSTRACT FROM AUTHOR]