The invention discloses a composite membrane information coating formula used by a plate joint laser imprinting machine and a preparation method thereof. The formula comprises the following components in percentage by weight: 35-45 percent of acrylic resin, 35-45 percent of acrylic polyol resin, 8-10 percent of iso-cyante resin, 3-4 percent of butanone, 3-4 percent of ethyl acetate, 3-4 percent of butyl acetate, 0.3-0.6 percent of ethanol and 0.2-0.3 percent of p-toluenesulfonicacid. The preparation method comprises the following steps of: dissolving the acrylic resin and the acrylic polyol resin into mixed solution of a solvent of the butanone and the ethyl acetate and evenly stirring according to the proportion of the formula to form pre-prepared mixed resin solution; when in use, diluting the p-toluenesulfonicacid with the butyl acetate and ethanol solution; adding the pre-prepared mixed resin solution; and adding the iso-cyante resin and evenly stirring. The composite membrane information coating formula is coated on a basement membrane for laser imprinting, can produce a thin membrane with 6,000 meters without plate blockage phenomenon and has high production efficinecy; and in addition, the product has excellent quality.