The invention relates to a scrape resistant high transmittance PC alloy resin composition which is prepared from the following raw materials in parts by weight: 10-90 parts of PC and 10-90 parts of polymethacrylate copolymer which is maleic anhydride-styrene-methyl methacrylate terpolymer P (MAH-St-MMA), wherein the content of the maleic anhydride is 5-30 wt%, and the weight-average molecular weight is 40,000-300,000g/mol; and the invention also provides a preparation method of the above composition. The scrape resistant high transmittance PC alloy resin composition has the advantages that: the maleic anhydride-styrene-methyl acrylate terpolymer and polycarbonate PC have good compatibility and high transparency after being blended, and the alloy resin prepared has high transmittance and is scrape resistant; the PC alloy resin composition of the invention can further contain PMMA, impact modifier, liquidity modifier, lubricant, release agent and other processing agent, and the PC alloy resin composition for various uses can be prepared; the PC alloy resin of the invention is relatively simple in manufacturing process and conducive to mass production.