The invention discloses graphene modified fire-proof paint and a preparation method thereof. The graphene modified fire-proof paint is prepared from a vinyl acetate-ethylene copolymer emulsion, ammonium polyphosphate, pentaerythritol, tripolycyanamide, graphene modified silicon dioxide powder, titanium dioxide, an additive and the balance water. The invention further discloses the preparation method of the graphene modified fire-proof paint. In the fire-proof paint, graphene can be stably dispersed, and moreover, due to the introduction of the two-dimensional material graphene, the problems are solved that after being dried completely, a coating is prone to cracking and poor in water resistance, and a foaming thermal-insulating layer is low in mechanical strength and easily falls off; thecompactness and the regularity of a carbon layer are improved, high-temperature cracking of the coating is prevented, and the fire-proof effect is improved.