Herein, gefitinib-loaded nanoparticles are prepared based on the flash nanoprecipitation (FNP) approach, which lead to kinetically frozen nanoparticles featuring good size control and stability over time. Folic acid-modified amphiphilic Dex-b-PLA is applied as the protective copolymer, and the formed nanoparticles (NPs) display decent biocompatibility and efficient cellular uptake rate due to the presence of the dextran blocks and target groups, respectively. Our study demonstrates a novel method for preparing lung cancer drug-loaded NPs that show potential for further therapeutic applications.