Fractional-order model (FOM) is recognized as a preferable model of Lithium-ion Battery because of the inherent mechanism and the simplicity of the parameters. However, the identification of its parameters is still difficult if just with a simple engineering process. This paper proposes a parameter identification method for the FOM, which combines a time-domain process and a frequency-domain process. The time-domain process is for identifying the fractional-order parameter of the model based on electrochemical impedance spectroscopy (EIS), and the frequency-domain process is for resistance and capacitor parameters of the model with a modified hybrid pulse power characteristic (HPPC). The inherent mechanism basis of the processes is described and the effectiveness of the method is verified both by constant current and dynamic experiments.