Analgesia and sedation are common clinical practices in intensive care unit. Approprite analgesia and sedation should be patient-oriented and disease-oriented. Understand the pharmacological characteristics of analgesic and sedative, individual light sedation on the basis of adequate analgesia to make the patient achieve the best condition. Opioids are considered the first-line drug class of choice to treat non-neuropathic pain in critically ill patients. Combine strategy can reduce total opioid dosage and avoid adverse effects. Benzodiazepines exposure is an independent risk factors for ICU delirium. Therefore, short-acting, easy-to-titrate agents such as propofol and dexmedetomidine were selected as the first line choice. Benzodiazepines should be reserved for specific indications, such as procedural sedation, seizures, alcohol and benzodiazepine withdrawal, apparent anxiety,agitation and deep sedation. Further research on how to rational application of analgesic and sedative is needed.