The invention discloses modified styrene-acrylic emulsion with a high glass transition temperature and a low film formation temperature. The modified styrene-acrylic emulsion comprises the following components in parts by weight: 50-60 parts of water, 0.2-0.4 part of a non-ionic surfactant, 0.5-1.0 part of an anionic surfactant, 0.1-0.15 part of sodium bicarbonate, 0.2-0.3 part of ammonium persulfate, 0.05-0.1 part of t-butyl hydroperoxide, 0.05-0.1 part of sodium formaldehyde sulfoxylate, a core monomer and a shell monomer, wherein the core monomer comprises 10-15 parts of styrene, 4-9 parts of methyl methacrylate, 1-3 parts of butyl acrylate, 0.5-1 part of acrylic acid and 1-3 parts of crosslinker KH570; and the shell monomer comprises 3-5 parts of styrene, 1-2 parts of methyl methacrylate, 9-12 parts of butyl acrylate, 0.5-1 part of acrylic acid, 1-2 parts of ammonia water and 0.1-0.2 part of bactericide. According to the modified styrene-acrylic emulsion, by virtue of reasonable design of the monomers, the theoretical glass transition temperature of the system reaches above 65 DEG C and the characteristics of hardness and non-return stickiness at a high temperature of the product are ensured.