Steam ejector plays a critical role in MED-TVC desalination system that can achieve a good balance between freshwater production and energy savings. In this study, a pressure regulation technology is proposed to optimize the entrained flow passage and thus improve the ejector performance. The theoretical basis is that there have some existing low-pressure potentials inside the ejector that can be used to alleviate the high-pressure effect and shock wave at the mixing chamber end. Then the feasibility verification and performance comparison of different pressure regulation schemes is implemented systematically. Analysis and research mainly pay attention to the influences of pressure regulations on the mass flow rate, the entrainment ratio and internal flow field. The results reveal that there is an optimum combination of pressure regulation schemes, by which a most considerable entrainment ratio improvement could be achieved, as large as 11.77% within the simulated conditions, and with 3.94% even under the design condition. More specifically, for the given steam ejector, TMCE pressure regulation could be used if the ejector operates under the design condition. For the off-design conditions, CMCE pressure regulation is the best choice if the back pressure is larger than 34 kPa, otherwise DMCE pressure regulation should be chosen. (C) 2018 Elsevier Ltd. All rights reserved.