Abstract: A combined approach of evaporation experiment and mathematical modeling is used to analyze the influence of osmotic potential on the bare soil evaporation rate.The result shows that the osmotic potential is proven to be the main reason for the decline of evaporation rates in saline soils when no salt precipitation occurs.The rate decline is almost linearly proportional to the decrease in osmotic potential, and is also affected by air temperature, air relative humidity, soil temperature, and soil matrix potential.When a constant water flux is supplied to the topsoil, the evaporation rate would always tend to be the constant value.However, the evaporation rate in saline soils is rather slower if the saline water is supplied to the topsoil, and the steady evaporation rate would tend to be a bit slower than the water supply rate.