Convenient methods for the preparation of gene delivery platforms based on branched low molecular weight polyethylenimine (PEI) were described. Firstly, PEI lipids, with a low molecular weight PEI headgroup and hexadecyl chain tail group, were prepared through a highly efficient ring-opening reaction of glycidyl hexadecyl ether (EpoxyC16) by amine from PEI. Then, the PEI lipids were used as a component of cationic liposomes and as a surfactant for the preparation of poly(D,L-lactide-co-glycolide) (PLGA) nanoparticle (NP) via solvent extraction/evaporation method. As potential effective gene delivery platforms, their preparation, size, size distribution, toxicities, plasmid DNA loading, in vitro transfection and intracellular trafficking were studied. Both facile platforms showed less toxicity and higher transfection efficacy when compared to high molecular weight PEI in vitro, and may have further versatile applications in the gene delivery field.