The paper considers the process of hydrodynamic and heat transfer of thin film thermal desalination plants with different methods of organization of the movement of seawater in the film (horizontal, vertical and jet-impact spraying). The regimes of these plants influence plant productivity, fresh water quality, decreasing the heating energy required for desalination. The investigation includes the development of a mathematical model of thin film water movement by heating surfaces. The equations for velocity values and flow stability conditions were obtained. The influence of the liquid stabilizing action on surface heating by hydrodynamic and heat transfer was established. Analysis of regimes of all plant types was made and equations for coefficients of heat transfer and hydrodynamic resistance were derived.