A novel PEGylated lipid and preparation methods thereof, a cationic liposome containing the lipid, a pharmaceutical composition containing the liposome, a formulation and application thereof. The PEGylated lipid can be used for modifying a liposome, and can be further modified and coupled with a targeting group and then used for modifying a liposome to obtain a liposome having the targeting group. Due to the presence of a long-chain PEG and the targeting group on the lipid, the modified liposome can avoid being removed by the reticuloendothelial system in a human body and realize a targeting function. Therefore, when the modified liposome delivers an active drug to cells or a patient, especially when delivering a nucleic acid or anti-tumor drug, the liposome can realize long circulation in vivo and improve the transport efficiency of drug, and has a targeting function, so the therapeutic effect of a drug is improved.