Abstract: Tannin-based foam, as a promising energy-saving material for buildings, has received increasing attention due to its light weight, excellent thermal insulation and flame retardancy. To improve the brittleness and enhance the compressive strength of tannin-based foams, tannin-bamboo powder bio-based foam (TBF) with a density of 110 kg/m³ was prepared using bamboo powder as an additive. The SEM testing revealed that the bamboo powder has good compatibility and reactivity with the resin, and can be uniformly distributed on the walls of the foam pores, which can strengthen the cross-linking between the substances, and pulverization rate testing demonstrated that the pulverization rate of TBF can be reduced to 2.69%. The use of bamboo powder to reinforce the tannin-based foam can effectively improve the compressibility of the foam ribs and walls, and its compressive strength (0.46 MPa) is increased by 80% compared with the standard tannin-based foam; at the same time, the bamboo powder also absorbs energy and reduces the generation and expansion of cracks. In addition, TBF has been proven to be highly flame retardant in use through flame retardancy tests. The tannin-bamboo powder bio-based foam prepared in this study has great potential for application in the field of wall insulation materials.