In order to study the influence of material property deterioration on the seismic performance of bridges during service, based on the principle of steel corrosion and Fick’s second law, this paper analyzed the deterioration law of steel and concrete material properties and obtained the degradation law of rubber bearing properties over time. According to the theory of seismic vulnerability and risk, a method was established to calculate the seismic reliability of bridges. With a reinforced concrete box girder bridge in China as an example, the seismic vulnerability curve, risk curve, and seismic reliability during the whole life cycle of the bridge were calculated. The research shows that: ① The bridge transcendence probability increases with the increase in peak acceleration a_PGA under different damage conditions. The common deterioration of the pier column and bearing has the greatest influence on the seismic damage of the bridge, and the influence of pier column deterioration on the seismic damage of the bridge is greater than that of bearing deterioration； ② A longer service life of the bridge means a greater bridge transcendence probability under the same seismic intensity, but the increasing range decreases with the increase in service time； ③ With the increase in service time, the seismic reliability index of the bridge under various damage conditions decreases continuously. Among them, the seismic reliability of the bridge under the common deterioration of pier column and bearing decreases most obviously. Pier column deterioration alone has a greater influence on the seismic reliability of the bridge than that of bearing deterioration alone； ④ A longer service time of the bridge indicates a greater seismic reliability difference between bridges with and without material deterioration considered.