The invention discloses a mildew-proof bamboo particle board and a preparing method thereof. The bamboo particle board is prepared by chipping and flaking a bamboo material to obtain bamboo particlesand conducting high temperature preprocessing, drying, gluing, pre-pressing and hot pressing. Bacteria carried in the bamboo particles are killed after the bamboo particles are subjected to high-temperature heat treatment, starch, sugar, protein and other chemical components are degenerated through high-temperature heat treatment and are not nutrients of mildew any more, and the mildew-proof performance of the bamboo particle board is effectively improved. In addition, the mildew-proof bamboo particle board uses the bamboo material short in growth cycle and bamboo material processing residuesas the raw materials, only an adhesive and a waterproof agent are added in the gluing step in the production process, no preservative, insect-resist agent and other harmful components are added, and the mildew-proof bamboo particle board is an environment-friendly artificial board and can be widely used as an indoor decoration material or used for manufacturing furniture.