A visual design and simulation package was developed for design and simulation of different types and configurations of desalination processes. Object-oriented programming with Visual Basic was used to offer a flexible reliable and friendly user-interface. The desalination plant components (named here as units), such as heat exchangers, flash chambers, evaporators, pumps, steam ejector, compressor, reverse osmosis membrane, pipes, etc., are stored as icons in a visual library. This visual library enables the user to construct different configurations by just clicking the mouse over the required units (icons). The interface aids both plant designers, operators and other users to perform different calculations such as energy, exergy, and thermoeconomics. In addition, the package enables designers to perform different modifications of an existing plant or to develop a conceptual design for new configurations. The present package offers great help not only to the designers and operators but also to researchers, educators and students. Some operating desalination plants were simulated with the package to show its reliability and flexibility. Typical desalination processes such as multistage flash, multi-effect evaporation, thermal vapor compression, mechanical vapor compression and reverse osmosis were simulated to show the wide scope and great capability of the package.