Ethylene oxide (EO) is an important raw material for producing ethylene carbonate (EC). However, the traditional method for the separation of EO from mixture gas by water in the refining process is high energy consumption. In this paper, two processes of manufacturing EC from EO mixture gas were studied by process simulation. Two processes for producing EC from EO mixture as raw materials without EO purification, called the OSAC process and the Modified OSAC process, were developed and assessed sys-tematically. Both processes use EC as the absorbent to capture EO, avoiding the separation process of EO from solution. For comparisons, the EC producing process containing EO absorption by water, EO refine-ment and carbonylation process were also modeled, which was called the ERC process. Three schemes were designed for the EO absorber using EC as absorbent. Compared with the initial absorber scheme, the optimal liquid–vapor ratio is reduced from 1.66 to 1.45 (mass). Moreover, the mass distribution anal-ysis for the three processes were carried out in the form of the material chain. It was found that, com-pared with the ERC process, the energy consumption of the OSAC and the Modified OSAC process is reduced by 56.89％and 30.03％, respectively. This work will provide helpful information for the industri-alization of the OSAC process.