The invention relates to a method of loading doxorubicin through folic acid targeted multifunctional hyperbranched polyethylenimine. The method includes adding an activated mPEG-COOH solution into a PEI solution, adding an activated FA-PEG-COOH solution, reacting under stirring to obtain PEI-mPEG-(PEG-FA), adding an FI solution into the PEI-mPEG-(PEG-FA) solution, reacting under stirring in dark, adding triethylamine and acetic anhydride, stirring, dialyzing, freeze-drying to obtain FA-mPEI, adding doxorubicin hydrochloride DOX.HCl deacidified in advance into an aqueous solution of the FA-mPEI, stirring in a dark place with an opening being uncovered, centrifuging, selecting a supernatant and drying. The PEI which is cheap and easily available is adopted as a base carrier, and the FA is adopted as a targeting agent, thus reducing the material cost. The method is free of adverse effects on a living body, simple, mild in conditions and easy to operate, and has a good prospect.