The invention relates to the technical field of plastic-processed finished product mixtures, and discloses a flame-retardant, impact-resistant and high-flow alloy material and a preparation method thereof. The material is prepared, by weight, polyacrylate nanoparticle latex grafted modified vinyl chloride composite resin, low molecular weight homogeneous polyvinyl chloride, a heat stabilizer, a lubricant and a modifier. The polyacrylate nanoparticle latex grafted modified vinyl chloride composite resin, the low molecular weight homogeneous polyvinyl chloride, the heat stabilizer, the lubricantand the modifier are mixed evenly at a high speed, the obtained first mixture is mixed at a low speed, and the obtained blend molding mixture is extruded and granulated to obtain the flame-retardant,impact-resistant and high-flow alloy material. The flame-retardant, impact-resistant and high-flow alloy material has the advantages of being high in impact toughness, good in fluidity and low in cost; in addition, the preparation method is simple, the technological requirements are low, and the obtained flame-retardant, impact-resistant and high-flow alloy material is wide in application.