Objective To evaluate the application value of focused assessment with sonography for trauma (FAST) in treatment of emergency thoracic and abdominal closed injury.Methods FAST examination was performed in 85 patients with thoracic and abdominal closed injury,to determine whether the thoracic and abdominal cavity,pericardial free effusion and abdominal parenchyma organ injury,and the results were compared with conventional ultrasonography,CT scan and operation results.Results FAST was (2.85 ± 1.15) min,conventional ultrasonography was (15.48 ±5.17) min,there was statistically significant difference (t =21.99,P ＜ 0.05).In 85 patients,10 cases were FAST positive,5 cases of abdominal cavity in that amount or a large number of free effusion,underwent emergency operation,postoperative intra abdominal parenchymal organs were confirmed as rupture and hemoperitoneum; 2 cases of renal rupture with perirenal hematoma,confirmed by the whole abdominal CT examination; 2 cases of thoracic free pneumatosis,effusion,confirmed by thoracic CT examination or closed thoracic drainage; 1 case of prompt hemopericardium,confirmed by the pericardium puncture.Conventional ultrasonography was positive in 11 patients,no statistically significant difference between them (P ＞ 0.05).The sensitivity,specificity,accuracy rate of FAST screening thoracic and abdominal closed injury was 10/12,100.0％ (73/73),97.6％ (83/85).Conclusions FAST has high sensitivity and specificity for thoracic and abdominal cavity,pericardial free effusion,check with short time,low environmental requirements,without moving the trauma patients,and may be out of sync with the fluid resuscitation and other emergency measures.For large quantities of trauma patients and patients with severe multiple trauma,FAST can quickly,accurately determine the existence of thoracic and abdominal closed injury,and provide guidance for clinical treatment,which has good application value.