ICU acquired weakness affects the recovery of critically ill patients and the quality of life after discharge. Early functional exercise can reduce the incidence of ICU acquired weakness and promote the recovery of patients. In this article,the necessity of early functional exercise for ICU patients is described firstly. Secondly,the assessment of early functional exercise is also summarized,including the specific contents of the initial and continuous assessment of early functional exercise. Besides,the current status and problems of the research on the implementation of early functional exercise,including progressive functional exercise and goal-oriented functional exercise,are reviewed. Lastly,the impediments to the implementation of early functional exercise are analyzed,and the corresponding countermeasures are proposed. The purpose of this study is to provide a reference for clinical and nursing staff to implement early functional exercise effectively and safely.