The invention discloses a branched-structure polyurethane-silicious polyacrylate hot melt adhesive and a preparation method thereof. The branched-structure polyurethane-silicious polyacrylate hot melt adhesive mainly comprises the following components of branched-structure polyurethane-silicious polyacrylate resin, tackifier, fillers, wax additive, light stabilizer and antioxidant, wherein the branched-structure polyurethane-silicious polyacrylate resin is a polymer specially synthesized for the invention. The preparation method of the branched-structure polyurethane-silicious polyacrylate hot melt adhesive comprises the following steps of: heating and melting the antioxidant, the light stabilizer, the tackifier and the wax additive according to weight ratio of the hot melt adhesive, controlling temperature, adding the branched-structure polyurethane-silicious polyacrylate resin and the fillers in batches while stirring, discharging after melting and uniformly mixing adhesive solution, cooling, slicing and forming to obtain the prepared hot melt adhesive. According to the branched-structure polyurethane-silicious polyacrylate hot melt adhesive and the preparation method thereof, the problems of poor heat resistance and low strength of the traditional EVA (ethylene-co-vinyl acetate) hot melt adhesives, high energy consumption for preparation, high melt temperature and poor construction performance of polyester hot melt adhesives, and poor weather resistance, poor storage stability and higher cost of moisture-curing polyurethane hot melt adhesive are solved.