Abstract:As the children in the paediatric intensive care unit(PICU) are in a strong stress environment, sympathetic nerves are prone to overexcitation and produce a “sympathetic storm”, which leads to a series of complications. Therefore, the treatment of sedation and analgesia is an important for critically ill children. There are a large number of clinical literature and guidelines supporting the selection of sedation depth and sedation evaluation methods in adults, but the high-quality clinical evidence in children is still insufficient. Thus, this review mainly discusses the relationship between different sedation depths and the prognosis of critically ill children, and will summarize the definition, selection and evaluation of sedation depth based on adult guidelines and existing literature.