Evaporation rate from the surface of freshly cast concrete in plastic stage under high temperature and low humidity environment was studied with research variables including wind speed and water cement ratio. The evaporation rate at concrete surface was determined based on the evaporation rate of the free water, which is capable of simulating the evaporation rate of the concrete under certain environmental conditions. The results show that the evaporation rate of concrete is equal to that of free water when the concrete surface is covered with bleeding water. During the process of evaporation, bleeding water gradually reduces and disappears.