Abstract: Nowadays, there is still no mature gene delivery system for safe and effective transfection on primary dendritic cells (DC). Herein, we constructed a liposome-based gene delivery system for primary DCs and optimized the preparation method to improve the transfection efficiency of siRNA on primary DCs. In this study, different methods, including co-incubation method, ethanol injection method, and protamine compound method, were used to prepare liposome/siRNA complexes based on different cationic lipids. Moreover, particle size, zeta potential, siRNA loading capacity, safety, stability, uptake efficiency and gene silencing efficiency of various liposome/siRNA complexes were detected to screen the optimal cationic lipid as well as its preparation method. We demonstrated that the OA2/siRNA delivery system prepared by the co-incubation method exhibited the best safety, uptake efficiency and gene silencing effect, compared to other siRNA delivery systems including the commercial Lipo2000. In summary, we provide a safe and effective gene delivery vector for primary DC cells through simple preparation method, which could also offer a gene delivery platform for other immune cells.