In order to enhance the penetration of small interference RNA against the polo-like kinase I (siPLK1) across BBB to treat glioblastoma (GBM), transferrin (Tf) modified magnetic nanoparticle (Tf-PEG-PLL/[email protected]) was prepared. The in vitro experiments indicated that Tf-PEG-PLL/[email protected] enhanced the cellular uptake of siPLK1, which resulted in an increase of gene silencing effect and cytotoxicity of Tf-PEG-PLL/[email protected] on U87 cells. Besides, Tf-PEG-PLL/[email protected] significantly inhibited the growth of U87 glioblastoma spheroids and markedly increased the BBB penetration efficiency of siPLK1 with the application of external magnetic field in in-vitro BBB model. The in vivo experiments indicated that siPLK1 selectively accumulated in the brain tissue, and markedly reduced tumor volume and prolonged the survival time of GBM-bearing mice after Tf-PEG-PLL/[email protected] was injected to GBM-bearing mice via tail vein. The above data indicated that magnet and transferrin co-modified nanoparticle enhanced siPLK1 penetration across BBB and increased its anti GBM activity in vivo.