Pretreatment and liquefaction of natural gas are two key links of offshore LNG-FPSO.The pressure swing adsorption(PSA)as natural gas purification and CO2 pre-cooling air expander cycle as natural gas liquefaction are selected and simulated and analyzed.The results show that

the energy consumption of the double layers adsorbents PSA is low

and the disadvantage of liquid absorbent with the wave shaking can be avoided by the process operation of the gas; and there is no liquid produced in the precooling and refrigeration processes of the CO2 pre-cooling air expander cycle

indicating its high safety; the above purification and liquefaction processes are suitable for offshore LNG platforms.