Background　The use of opioid-based intravenous controlled analgesia in children helps to relieve moderate to severe postoperative pain, helps to improve the satisfaction of children and their families and improves the prognosis.　Objective　Investigate the safety and efficacy of intravenous controlled-analgesia induced respiratory depression in children and to improve the safety and efficacy of postoperative pain management in pediatric.　Content　It consists of side effects of opiods, postoperative analgesia management and analgesic itself and other adverse factors, especially drug-induced respiratory depression in children after intravenous controlled-analgesic safety concern.　Trend　The trend of effective prevention and treatment of postoperative intravenous patient-controlled analgesic side effects is particularly important.