The invention discloses a special environment-friendly waterproof agent for flame retardance of an artificial board and a preparation method of the special environment-friendly waterproof agent. The special environment-friendly waterproof agent is prepared from 10%-16% of a polypropylene random copolymer, 6%-8% of coated ammonium polyphosphate, 3%-6% of melamine, 1%-3% of copper hydroxide, 1%-2% of nano ceramic clay, 3%-5% of expansible graphite, 5%-7% of lanolin, 1%-3% of an antioxidant, a silane coupling agent and silicone oil. With the adoption of the waterproof agent, the board has a dampproof function, the problem of reduction of flame retardant property after a flame retardant is affected with damp is effectively solved, the board sticking rate is reduced, 24h water absorption expansion rate of the flame-retardant board is increased, and the degree of lubrication is increased; the problem of reduction of overall mechanical strength is solved, the problem about water absorption capability of the board is solved, the delamination phenomenon is eliminated, furthermore, an unexpected effect is realized, anti-bacterial and formaldehyde-reducing functions are achieved, besides, brightness of the board can be improved, and wood attractiveness is enhanced.