The invention discloses a prepreg for a high-toughness halogen-free CEM-3 copper-clad laminate. The prepreg is prepared by the following preparation method: coating electronic glass fiber cloth with glue liquid for the high-toughness halogen-free CEM-3 copper-clad laminate and drying to obtain a veneering prepreg; and coating glass felt with the glue liquid for the high-toughness halogen-free CEM-3 copper-clad laminate and drying to obtain a sandwich prepreg, wherein the glue liquid for the high-toughness halogen-free CEM-3 copper-clad laminate comprises the following raw material components in parts by weight: 75 to 120 parts of phenolic epoxy resin, 300 to 450 parts of flame-retardant modified liquid halogen-free epoxy resin, 150 to 250 parts of flame-retardant modified solid halogen-free epoxy resin, 25 to 50 parts of curing agent, 0.10 to 0.30 part of curing accelerator and 100 to 200 parts of organic solvent. The prepreg for the high-toughness halogen-free CEM-3 copper-clad laminate not only has high heat resistance and chemical resistance, but also can reduce environmental pollution.