The present invention relates to a drug delivery system (DDS) for crossing the blood-brain barrier (BBB) formed by self-assembly of an amphiphilic block copolymer, comprising a self-assembled structure having an average diameter of 5 nm to 20 nm of a core-shell structure comprising a hydrophobic core and a hydrophilic shell and a hydrophobic drug supported in the hydrophobic core of the self-assembled structure, a pharmaceutical composition for preventing or treating cerebral diseases comprising the drug delivery system as an active ingredient, and a preparation method of the drug delivery system.
