A method and system for estimating a state of health using battery model parameters are provided. The system includes a battery model parameter extractor that is configured to extract liquid-phase diffusivity of Li-ion parameters and a storage unit that is configured to store a mapping table in which states of health (SOH) for each liquid-phase diffusivity of Li-ion parameter are mapped. In addition, a SOH estimator is configured to use the mapping table to estimate the SOH that corresponds to a liquid-phase diffusivity of Li-ion extracted from the battery model parameter extractor.