Abstarct: Bridges as key elements in transportation networks, are subjected to contionuous degradation. These structures require an ongoing screening to give an early warning if the bridge becomes unsafe. In recent years a shift of instrumentation from the bridge to a passing vehicle to collect the indirect measurements, has occurred due to advantages that these methods provide. On the other hand, Charges System Search (CSS) has rarely been used for structural health monitoring. But since it dose not require any gradient information, it has been used for structural applications. This paper proposes an indirect method baxsed on optimization, to identifiy dynamic parameters of bridge and bridge stiffness. The method used in this investigation is baxsed on optimization method rather than conventional transforms from time domain to frequency domain. The results show that the method is successful in using vehicle accelerations as input to the algorithm and identify bridge stiffness and dynamic parameters of vehicle-bridge system with good accuracy.