The intestinal flora and the intestinal environment in which it resides together constitute the intestinal microecosystem,it is significantly disturbed in neurocritical ill patients, as manifested by the decrease of bacterial diversity, an increase of pathogen, and the destruction of the intestinal barrier. Appropriate enteral nutrition is effective in maintaining intestinal barrier stability, regulating intestinal immune function, inhibiting intestinal inflammation, and regulating specific intestinal microbiota and intestinal function. It is important for sustaining intestinal microecological balance, reducing clinical complications in patients, and is a new target for the treatment of neurocritical ill patients. This review elaborates the alteration of intestinal microecology and treatment options recommended by current clinical guidelines in neurocritical ill patients and summarizes the research progress of the effects of enteral nutrition and several nutritional additives on intestinal flora and intestinal functions, to provide a reference for the follow-up research.