The present invention relates to an acrylated semi-crystalline hyperbranched polyurethane oligomer and a preparation method thereof, which is characterized in that on the basis of the synthesis of hyperbranched polyurethane oligomer, it adopts a two-step process to make modifications to form a methacrylic and/or acrylic double bond and a long carbon chain with a carbon atom number higher than 10 or a benzene ring or a naphthalene ring at the terminals. The obtained oligomer has a lower melting point and a higher glass transition temperature and can be cured by means of radiation, and the curing rate is high enough to effectively improve production efficiency and save energy to form a cured film having a higher hardness and excellent thermal stability. The raw materials used in the method of the invention are easily obtained, and the method is suitable for large-scale production in industry.