The invention relates to a poly(n-butyl cyanoacrylate) nanoparticle with dual modifications, a drug delivery system comprising the nanoparticle, and a method for preparing the nanoparticle or the drug delivery system. The nanoparticle is modified with a first modifier and a second modifier on the surface, the first modifier is a hydrophilic polymer, and the second modifier is an amino acid and/or a lipid. The invention further relates to a use of the nanoparticle in promoting drug penetration across the blood brain barrier in a subject.