Ultraviolet-resistant, mildew-proof and flame-retardant PVC and preparation method thereof

The invention relates to the technical field of PVC, specifically to ultraviolet-resistant, mildew-proof and flame-retardant PVC and a preparation method thereof. The ultraviolet-resistant, mildew-proof and flame-retardant PVC comprises PVC powder, a plasticizer, a filling agent, a heat stabilizer, a lubricant, a flame retardant, an ultraviolet-resistant agent, a mildew inhibitor and an antioxidant. According to the invention, through a solvent precipitation regeneration principle, PA12 is used for coating nanometer calcium carbonate; a prepared filling agent has a core-shell structure; the PA12 has the characteristic of strong polarity, but relative to the nanometer calcium carbonate, the PA12 in PVC is slightly good in compatibility; meanwhile, the melting processing temperature of the PA12 is 200 DEG C or above; thus, the PA12 is not in a molten state in the PVC blending modification process and can well maintain an island structure distributed in a PVC matrix, so the rigidity and the toughness of the PVC