The invention relates to an efficient flame retardant dispersion liquid for epoxy resin and a preparation method thereof. The efficient flame retardant dispersion liquid is prepared by dispersing graphite oxide in a solvent and compounding the same with a phosphorus azine compound; the phosphorus azine compound is 5,10-hydro-phosphorus azin-10-oxide and a derivative thereof. The consolute temperature of the efficient flame retardant dispersion liquid for epoxy resin provided by the invention with an epoxy resin prepolymer is low, and the epoxy resin system has an excellent flame retardant effect (the epoxy resin cured product passes a UL94 V0 grade when the dosage is 2.5 parts) under the condition of relatively less dosage, and the mechanical strength and the thermal stability of the epoxyresin are not influenced, or even are improved.