The invention relates to the technical field of polyvinyl chloride (PVC) composite materials, in particular to an ultraviolet-proof environmental-friendly PVC modified material and a preparation method of the ultraviolet-proof environmental-friendly PVC modified material. The modified material is composed of, by weight, 80-120 parts of PVC resin, 30-70 parts of filling agents, 41-80 parts of plasticizer, 1-10 parts of fire retardant, 1-10 parts of stabilizer, 5-15 parts of impact modifier, 0.2-2 parts of lubricating agents, 0.5-1.5 parts of light stabilizer and 0.2-1 part of antioxidant. The preparation method comprises the steps of weighing the raw materials according to the parts by weight, mixing the raw materials, after stirring, extruding prills through a twin-screw extruder, and obtaining the modified material. The modified material has the advantages of ultraviolet protection and oxygen resistance, service life of the PVC material exposed in air is greatly improved, environment is protected, strength is high, a fire retardant effect is good, compression performance and toughness are strong, processability is good, and an overall property is good.