Abstract: The basic Arrhenius equation in the physical-chemical reaction is introduced to control the hydration process of the cement. The concept of “quivalent age”is put forward to describe the influence of temperature on the elastic modulus of concrete. We calculate the temperature field of some RCC dam under construction, with which we step into the stress calculation considering the “quivalent age” The temperature and the gravity creep stress of the dam are both included in the total stresses. Also, the total stresses with the normal temperature of 20℃ of the elastic modulus are computed. These two kinds of stress fields are compared. It is found that the concrete is more vulnerable when the temperature effect on the elastic modulus of concrete is considered.