Abstract: The processes for liquefied natural gas separation，including conventional distillation，thermally coupled distillation，side-stripper，double-effect distillation and heat-integrated distillation were simulated by using rigorous models and their energy consumptions were compared. The simulated results showed that the complex distillation processes consume much less energy and operation cost than conventional distillation. The thermally coupled distillation saves energy by 21.4%，side-stripper by 13.3%，double-effect distillation by 34.7% while heat-integrated distillation by 37.6%，against the conventional process. All the complex distillation processes have good prospects of application and double-effect distillation and thermally coupled distillation arrangements are superior.