Nucleic acid immunization is encapsulated in liposome by delivering RNA PEGylated. The RNA encodes immunogene interested. There is the PEG average molecular weight to be higher than 3kDa only a little ratio 11kDa. Therefore, the present invention provides have double-deck liposomal encapsulated aqueous core, in attached drawing: (I) includes at least one lipid in lipid bilayer, including a polyalkylene glycol moiety, so that polyethylene glycol occurs in external liposome, wherein the average molecular weight of polyethylene glycol is higher than 3kDa only a little ratio 11kDa (II) aqueous core includes which encoding immunogens of RNA. These liposomes are suitable for delivering RNA to vertebrate cells, therefore they can be used as pharmaceutical composition ingredient for a variety of disease immune objects.
