In order to economically exploit seawater chemical resources,it is essential to adequately adopt the local natural resources such as the energy of the wind and sun,i.e.,solar pond techniques.The simulating isothermal evaporation experiment as similar as the climate conditions in the Gulf of Thailand was designed to demonstrate the enrichment behaviours of sodium,potassium,magnesium,calcium and the rare elements including lithium,bromine,rubidium,and caesium in seawater in the Gulf of Thailand.Through this experimental study,a series of liquid- and solid phase samples through evaporating after filtrating were obtained and analyzed to reveal the enriched behaviours of sodium,potassium,magnesium,calcium.The experiment results showed that potassium ion was gradually enriched in the liquid phase in the first stage,and then it was crystallized out in the forms of carnallite and only a few of potassium chloride formed at the late evaporating stage.Meanwhile,the concentrations of lithium ion and bromine ion are measured corresponding to flame atomic absorption spectrophotometer and spectrophotometer to reveal the enrichment behaviors of lithium and bromine in brine during isothermal evaporating process.The results of experiment showed that lithium was enriched constantly at the first stage of evaporating,and then significantly up to 18.85 mg/L of lithium in solution; bromine in the liquid phase was enriched as similar as lithium with the highest concentration up to 6.0g/L in the mother liquor.The thesis provides an important reference for the development process of bromine and lithium extraction from the seawater in the Gulf of Thailand.Those results provided a valuable reference for the comprehensive utilization of seawater in the Gulf of Thailand.