Objective To understand early mobilization status of critically ill patients implemented by ICU nurses, and to analyze the perceived barriers of the implementation, so as to provide reference for promoting early mobilization of ICU critically ill patients. Methods A total of 921 ICU nurses from 48 tertiary hospitals were investigated using a self-designed questionnaire.Results Totally 91.53% ICU nurses had carried out early mobilization for critically ill patients, the major forms of mobilization were passive activity in bed (65.37%) and sitting up in bed (64.82%); and 63.08% nurses had received early mobilization related training and education, 53.42% stated that there was no multidisciplinary team supporting and guiding the practice of early mobilization. Lack of time, medical disputes, lack of physicians′ order and informed consent were the main barriers of nurses′ individual level; lack of the resources of human, equipment and training were the major organizational barriers; and unstable medical condition was the most important barrier of patients′ level. Conclusion The implementation of early mobilization for critically ill patients by ICU nurses is not good, the mobilization form is not diverse, and some barriers influence early mobilization. It is necessary to strengthen the construction of early mobilization culture, optimize resource allocation and establish early mobilization procedure to promote early mobilization for critically ill patients, then to improve their prognosis.