Abstract: As the scale and voltage level of electrochemical energy storage systems continue to increase, greater emphasis has been placed on enhancing the sensitivity and accuracy of fault monitoring and diagnosis of energy storage systems, as well as early warning and isolation of faults. Focusing on the condition monitoring and fault diagnosis of large-scale electrochemical energy storage systems, this paper summarizes and analyzes the research status of fault monitoring and diagnosis of electrochemical energy storage systems at home and abroad from three aspects: typical faults and their state variable response characteristics, online monitoring and multi-dimensional sensing, and fault diagnosis and identification methods. First, characteristics of typical faults such as thermal runaway and insulation failure are presented. Subsequently, the application status in electrochemical energy storage systems of various in-situ online monitoring methods such as gas sensor and fiber grating sensing, as well as their advantages and disadvantages, are analyzed. The feasibility of multi-dimensional sensing applied to large-scale electrochemical energy storage systems is explored. In addition, a variety of fault diagnosis methods such as model-based methods and non-model-driven methods, and their limitations are summarized. The paper finally analyzes the current research challenges and unsettled key problems.