The invention discloses a waterproof high-strength composite board which comprises a base layer. The top of the base layer is fixedly connected with a reinforcing layer, the top of the reinforcing layer is bonded with a heat-insulating layer, the top of the heat-insulating layer is bonded with a waterproof layer, the top of the waterproof layer is fixedly connected with a top plate, a polyethylene adhesive tape is arranged on the upper surface of the top plate, the waterproof layer comprises a polymethyl methacrylate layer, the top of the polymethyl methacrylate layer is provided with a water-absorbing sponge, the top of the water-absorbing sponge is bonded with an anti-scaling layer, and the reinforcing layer comprises two rubber pad layers. By arranging the base layer, the reinforcing layer, the heat-insulating layer, the waterproof layer, the top plate and the polyethylene adhesive tape and improving the waterproof layer, waterproof effect is realized under action of the polymethyl methacrylate layer, the water-absorbing sponge, the anti-scaling layer and a transparent adhesive tape, quality of the composite board is improved, and convenience is brought to use.