The present invention relates to a waterproof board and its manufacturing method, belongs to the technical field of floorboard and wallboards. The waterproof board includes waterproof layer and wear-resistant layer and the groove and ten on arranged on both side of said board respectively. Said wear-resistant layer is affixed onto said waterproof layer and said waterproof layer is made of the extrusion materials mainly including the resin and bamboo powder. The density of said waterproof layer is 0.60 kg/cm3-0.95 kg/cm3. The board of present invention is featured of high strength, good tensile strength, not easy to break; low water absorption rate, good waterproof performance; strong stability, less susceptible to deform due to changes in temperature or water immersion; light weight, more comfortable tactility, and further decreasing the material and transportation costs.