The invention provides a multifunctional nano-biomaterial transfection reagent with an effect of treating parkinsonism by gene, as well as a preparation method and application thereof. According to the method, a nerve growth factor (NGF) is immobilized on the surface of a hydrogel coated ferroferric oxide nano-particle (Fe3O4-OA-NAPI-AA) by virtue of a photo-grafting method, and plasmid DNA (Deoxyribonucleic Acid) capable of interfering with alpha-synuclein synthesis is adsorbed. The nano-material transfection reagent acts on the cell of an MPP+ (1-methyl-4-phenylpyridinium) induced in-vitro parkinsonism model PC12, and cell apoptosis is remarkably inhibited, wherein expression of the nerve growth factor receptor (NGFR) is up-regulated, expression of alpha-synuclein is down-regulated, and classic apoptosis pathway of BAX, P53 and Bcl-2 is influenced so as to achieve the aim of treating parkinsonism. The nano-material transfection reagent is non-toxic and less in side effects, can smoothly carry a gene to enter cells, is remarkable in action, and is worthy of popularization and application of parkinsonism treatment.