The invention relates to a flame retardant polyurethane composite material and a preparation method thereof. The traditional flame retardant polyurethane foamed material has a poor use effect. The flame retardant polyurethane composite material provided by the invention is a mixed system comprising 70-99wt% of flame retardant polyurethane and 1-30% of blending type fire retardant, wherein the blending type fire retardant is one or more than one of ammonium polyphosphate, melamine, melamine cyanurate acid, polysiloxane, graphine, a carbon nano tube and kaolin, the fire retardant polyurethane is a random copolymer consisting of a polycarbonate unit, a polyether and an isocyanate unit. The preparation method of the flame retardant polyurethane composite material comprises the following stepsof: firstly, preparing fire retardant polyalcohol; then, mixing the fire retardant polyalcohol and the blending type fire retardant into a mixed system; and then adding polyisocyanates into the mixedsystem and reacting to finally obtain the flame retardant polyurethane composite material. The flame retardant polyurethane composite material prepared by using the preparation method disclosed by the invention has the advantages of excellent fire retardance, low-fogging performance and low-gas-releasing performance.