Abstract: This paper reports a novel piezoelectric material accurate characterization method including loss characteristics,which is based upon Simulated Annealing（SA） optimization algorithm.With this method,lead metaniobate and 1-3 piezocomposite samples under thickness extensional vibration mode were studied.The optimized electrical impedance resonant characteristics of these samples match the measurement data very well,which verifies that the reported method can precisely characterize piezoelectric materials with loss properties.