Abstract: Electrochemical Impedance Spectroscopy (EIS) technology has been widely adopted for online evaluation of the State of Health (SOH) of Lithium-ion Batteries (LIBs). Currently, significant progress has been made in research on SOH evaluation of lithium batteries based on EIS both domestically and internationally. In basic research, EIS technology operates on specific principles, with its parameters closely related to battery health status. The testing process is standardized and methodical, presenting results in diverse formats, and has found widespread application across various aspects of battery research. In terms of evaluation methods, continuous innovation has evolved from analyzing parameter correlations to constructing predictive models. Despite significant achievements in data processing, challenges persist regarding data complexity, model limitations, and real-time implementation issues. This article reviews recent research progress on online assessment methods for lithium battery state of health based on EIS analysis, covering the basic principles of EIS technology, common EIS analysis methods, data processing and modeling techniques, as well as applications in battery management systems. The review emphasizes current research challenges and future development directions in this field.