Self-bonding technology is a forming method utilized for the production of bio-composites with notable advantages in terms of high strength and water resistance, while also being free from formaldehyde. The successful achievement of high-strength self-bonding biomaterials has been demonstrated, however, most of these achievements have relied on various surface chemical modifications with limited attention given to exploring non-additive approaches. This study aimed to investigate the feasibility of self-bonding formation through examining the effects of particle dispersion, lignin melting, and chemical bonding, in distinct unit morphologies without the use of any chemical additives. Also, the self-bonding mechanism of bamboo based composites (BBCs) was revealed, by examination of its microstructure, chemical composition and thermal stability. The findings indicated that raw component morphologies based on power, fiber, and bundle all effectively achieved high-strength self-bonding structures at a temperature of 155 °C, a pressure of 55 MPa, and a duration time of 60 min. The density of the BBCs approached that of solid cell wall in bamboo, reaching a maximum of 1.44 g/cm3. The morphology of raw components had significant effect on the self-bonding performance of BBCs, with the powder exhibiting the highest performance, followed by the bundles, and the fibers showing the lowest. The powder-based BBC demonstrated a remarkable flexural strength of 61 MPa, a notable surface hardness of 32.5 kgf/mm and low 24 h thickness swelling of 6.8 %, all much more excellent than those observed in ordinary panels. The BBCs demonstrated the benefits of being environmentally friendly (free from formaldehyde), processing excellent water resistance and strong mechanical strengths. They were suitable for use in high-humidity environments and can meet the requirements for strong load-bearing conditions, even replacing some metal sliding bearing materials.