Overloads of vehicle may cause damage to bridge structures, and how to assess the safety influence of heavy vehicles crossing the prototype bridge is one of the challenges. In this report, using a large amount of monitored data collected from the structural health monitoring system (SHMS) in service of the prototype bridge, of which the bridge type is large-span continuous rigid frame bridge, and adopting FEM simulation technique, we suggested a dynamic reliability assessment method in the report to assess the safety impact of heavy vehicles on the prototype bridge during operation. In the first place, by using the health monitored strain data, of which the selected monitored data time range is before the opening of traffic, the quasi dynamic reliability around the embedded sensor with no traffic load effects is obtained; then, with FEM technology, the FEM simulation model of one main span of the prototype bridge is built by using ANSYS software and then the dynamic reliability when the heavy vehicles crossing the prototype bridge corresponding to the middle-span web plate is comprehensively analyzed and discussed. At last, assuming that the main beam stress state change is in the stage of approximately linear elasticity under heavy vehicle loads impact, the authors got the impact level of heavy vehicles effects on the dynamic reliability of the prototype bridge. Based on a large number of field measured data, the dynamic reliability value calculated by our proposed methodology is more accurate. The method suggested in the paper can do good for not only the traffic management but also the damage analysis of bridges