Inclusion Criteria:  Acquisition of informed consent, Patients with hip fracture surgery under spinal anesthesia, Grade I to III based on American Society of Anesthesiologists ASA classification, Age ≥65.  Exclusion Criteria:  There was a history of cardiovascular and cerebrovascular adverse events in the past six months, including myocardial infarction, angina pectoris, severe arrhythmia, stroke or transient ischemic attack (TIA) Heart failure (NYHA III / IV and / or LVEF < 30%) Bradycardia Respiratory failure (need oxygen) Glasgow Coma Scale ≤ 14 points Severe hepatic and renal insufficiency (child Pugh grade B or C) Preoperative cognitive impairment or sedative drugs (benzodiazepines, etc.). Adverse reactions such as allergy to dexmedetomidine or / or propofol Preoperative bilateral hip fracture or other trauma need simultaneous operation Contraindications of spinal anesthesia