A distributed damage identification approach under moving vehicle loads is presented based on dynamic response sensitivity. Numerical studies are carried out on a simply supported beam under a vehicle with nonlinear springs for identication of distributed damage due to the crack. Combined Newmark direct integration method and Runge-kutta method are used to calculate the dynamic responses of the coupled bridge-vehicle system. The numerical results show that the distributed damage(s) can be identified accurately even with 5% noise in the measured acceleration data. And more accelerometers are needed if there are multiple cracks in the bridge.