Abstract: Research on LNG liquefaction process with double mixed refrigerant(DMR)based on the main plate-fin heat exchanger(PFHE)is carried out:The ternary mixed refrigerant of C₂H₆-C₃H₈-C₄H₁₀ with heavy components and high boiling point were used for throttling refrigeration cycle in precooling stage,and the ternary mixed refrigerant of CHC₂H₄-N₂ with light components and low boiling point were used for throttling refrigeration cycle in liquefaction and supercooled stages.The three-stage plate-fin heat exchanger was used as the main liquefaction equipment in PFHE-DMR liquefaction process contained two relatively independent refrigeration cycles with ternary mixed refrigerant.The results show that the PFHE-DMR liquefaction process can entirely replace MCHE-DMR liquefaction process.Compared with C3/MR liquefaction process,it can effectively improve the refrigeration efficiency.The three-stage PFHE with simple and compact structure has higher heat transfer efficiency and smaller heat transfer area when compared with three-stage MCHE.