A desalination system through mechanical vapor compression (MVC), coupling with an organic Rankine cycle (ORC) to drive the steam compressor, is proposed in this paper. Integrated mechanisms of the coupled desalination system are simulated and demonstrated based on the first and second law of thermodynamics, and the corresponding thermal performance is analyzed. Based on the system characteristics at the designed conditions for five types of working fluid, top temperature at the outlet of the boiler and the ambient temperature are designated to illustrate the evocable influence principles. It is observed that the variation trend of the performance both for the ORC and MVC is similar, and the maximum values of the freshwater production and gained output ratio (GOR) are acquired, which are very close for all types of the prescribed working fluid, with mw=1.09kgs-1 and GOR=3.15 for the case of R245fa. Moreover, it is also obtained that a higher top temperature and a lower ambient temperature are beneficial both for the freshwater production and energy conversion efficiency.