Adaptive delayed inverse model of mechanical system is adopted to determine time histories of multiple input forces aimed at the shortcoming that existing inverse system method relies on the state-space model. Adaptive algorithm is applied to identify delayed inverse model, followed by time domain force estimation using operational response combined with inverse model of mechanical system. Multi-input forces of simply supported beam were reconstructed by dynamic accelerations without and with noise disturbance. Simulation results illustrate that reconstruction accuracy decrease under noise condition but relatively satisfied and the method for multi-input identification is feasible. Furthermore, this method is validated experimentally.