The effect of sustained low temperature environment on the hydration heat of concrete was important for quantitative analysis of the hydration heat of concrete and for determination of the computing model for the hydration heat of concrete considering the effect of sustained low temperature of cast in place bored bridge piles in the construction of the Qinghai Tibet railway. The model was based on the monitored data to calculate the hydration heat of cement paste under the condition of sustained low temperature environment ((3±1)℃, (8±1)℃, (13±1)℃). Through experiments it is concluded that the hydration heat of cement paste under the condition of sustained low temperature environment is less than that of cement paste without any temperature limits, and this conclusion will be more obvious when the temperature of environment becomes lower. At last, through analysis of experimental data and the fitting to complete the computing model considering the hydration heat of cement paste under the condition of sustained low temperature environment, the results show that the model is in good agreement with the practice, and can be used to predict the hydration heat of cement paste under the condition of different sustained low temperature environment, in addition, it has some advantages such as simple formula, definite physical meaning and high accuracy, and it can be used to some applied engineering problems.