Objective To study the causes of rehematomas after operations of traumatic hematomas of perisylvian area.Methods The causes of 50 cases of rehematoma after operation were analyzed retrospectively.Results The big hematoma in primary contusion and laceration of brain happened in 19 cases(38%),delayed epidural hematoma in opposite side in 15 cases(30%),increased intracerebral hematoma in 9 cases(18%),epidural hematoma in primary area in 3 cases(6%),subdural hematoma caused by postoperative lumbaropuncture in 3 cases(6%),hematoma in encephalonecrosis in 1 case(2%).Conclusion Insuitable operation and hemostasis are the main causes of rehemorrhage,and fracture line in the opposite side,and thrombocytopenia are high risk factors of rehematoma.