In this paper a twostage vacuum ejector model is proposed, which is applied in the multieffect distillation with thermal vapor compressor (MEDTVC) system, and can improve the vacuum degree and operating efficiency of the system. A scale ratio of 1∶2 between the key dimensions of the two stage ejectors is proposed in the ejector structure design. In order to verify the structure and investigate the complex flow field inside the twostage ejector, the computational fluid dynamics (CFD) simulation software is adopted to carry out the modeling and simulation analysis of the ejector, and the inner flow field characteristics are presented. In order to investigate the influence of primary flow pressure on the performance of the ejector, the primary flow pressure was increased from 550 kPa to 630 kPa while the suction pressure and back pressure were fixed. It was found that the entrainment ratio of the ejector rises firstly, and then reaches a maximum value of 0073; after the maximum point, it begins to decrease with the increasing of the primary flow pressure. The twostage ejector can achieve a vacuum degree of around 58 kPa under the condition of primary flow pressure of 600kPa and back pressure of 100 kPa, which indicates that the proposed structure can effectively improve the operating efficiency and reduce energy consumption of the MEDTVC system.