The European Society of Intensive Care Medicine (ESICM) issued the second consensus on the assessment of sublingual microcirculation in critically ill patients. This paper interprets the consensus for clinicians about: what is microcirculation, how to observe microcirculation, and the details of microcirculation images collection and parameters analysis. Besides, this paper illustrates the relationship between microcirculation alternation and shock, it also evaluates the present situation and future development of microcirculation monitoring.