A mechanical vapor compression(MVC)based desalination system for oilfield waste water is proposed to combat the difficulties resulted from complicated and strongly polluting pollutants of the waste water in using membrane methods. The complete mathematical model for process simulation and design is developed for the MVC-based oilfield waste water desalination system and the influences of the heat transfer temperature difference of falling-film evaporators，waste water temperature and evaporation temperature on the system performance are analyzed. The results show that the temperature difference is the controlling factor that determines the specific heat transfer area and the specific compression work of the system. Reducing this temperature difference will directly decrease the specific compression work and increase the specific heat transfer area. Higher waste water temperature results in a slight decrease in the specific heat transfer area，which demonstrates that the system is highly perfect in thermodynamics. The results also show that increasing evaporation temperature may significantly improve the performance of the system.