The present invention relates to asymmetric liposomes for high encapsulation efficiency of nucleic acids and hydrophilic anionic compounds, and to a method for preparing same, and specifically, to asymmetric liposomes consisting of a cationic lipid having a small head group as an internal lipid and a neutral or PEGylated lipid having a big head group as an external lipid, wherein nucleic acids and/or anionic compounds are encapsulated in the internal lipid. According to the present invention, asymmetric liposomes, in which nucleic acids and hydrophilic anionic compounds are encapsulated with high efficiency, may be prepared, and thus the same may be used for various purposes, such as gene therapy, and the delivery of hydrophilic anionic drugs which are difficult to prepare as prodrugs, and drug delivery, imaging, etc. can be carried out by encapsulating a fluorescent contrast agent in the liposome.