Abstract: Based on the analysis of heat and mass transfer and an empirical correlation, a new desalination unit which utilizes solar or waste energy has been developed and tested. In this desalination, a considerable fraction of the latent and sensible heat was successfully recycled and utilized for enhancing falling evaporation-condensation and preheating seawater via remaining heat. The performance of the unit was tested through experiments using an electric heater as heat source. The results indicate that the unit has excellent transient-state performance for effective heat and mass transfer. As a result of the unit operating with a solar system under practical weather conditions, the yield was about five times greater than that of a conventional single solar basin still with the same thermal energy input. The main factors which influence the freshwater yield were researched and analyzed. The reasonable ranges of some parameters were presented.