Objective：To investigate the construction，characterization，and role of nanomicelles composed of fluorinated polyethyleneimine（PEI）derivatives in gene delivery across the blood-brain barrier（BBB）. Methods：PEI-heptafluorobutyric anhydride （HFAA）was synthesized through a chemical reaction between PEI and HFAA，followed by amide reaction with sinapic acid（SA）to obtain PEI-HFAA-SA（referred as SPF）. Finally，PEI-HFAA-SA@PS80（referred as SPFT）was obtained by encapsulating polysorbitol 80（PS80）within SPF. The molecular bonds and elemental composition of SPFT were analyzed using Fourier transformation infrared absorption spectroscopy，fluorine nuclear magnetic resonance（NMR），and hydrogen NMR spectroscopy. The hydrodynamic particle size，plasmid adsorption and protection capacity，stability and morphology of the carrier-plasmid complex were further characterized by dynamic light scattering experiments，agarose coagulation experiments and scanning electron microscopy observations，respectively. The gene transfection efficiency and cytotoxicity of SPFT were investigated in mouse glioma cell line Neuro 2a. SPFT carrying green fluoresant protein expression plasmid was injected into C57BL/6J mice by tail vein to observe its distribution in brain tissues and the effect of gene transfection within the BBB. Results：SA and HFAA were modified to synthesize SFPT，which was then wrapped in PS80. SPFT had a hydrodynamic particle size of 100 to 200 nm while exhibiting significant loading capacity for plasmids along with effective protection against degradation. In vitro experiments revealed that SPFT possessed excellent transfection ability and biocompatibility. In vivo experiments showed that SPFT accumulated in the brain successfully and crossed the BBB to deliver the gene effectively after tail vein injection into mice. Conclusion：SPFT exhibits a good biocompatibility and demonstrates an efficient gene delivery across the BBB，presenting a novel approach for drug administration in neurological disorders.