Abstract: A new method was proposed to improve the calculation efficiency of time-dependent reliability analysis for bridges. Based on the basic theory of structural reliability, the proposed method utilizes the Taylor expansion to simplify the traditional formula in an integration expression as a new formula in an algebraic expression, which essentially improves the calculation efficiency. In order to consider the uncertainties associated with the initial resistance and the degradation process, an explicit formula for time-dependent reliability analysis was also presented using a total probabilistic theorem. The proposed method was applied to the time-dependent reliability analysis of an RC bridge, and the results were compared with that associated with Monte Carlo simulation method to demonstrate the accuracy and high efficiency of the new method.