Proximal femoral nail antirotation（PFNA） is a common internal fixation method for intertrochanteric fractures. Arterial injury after surgical fixation is a rare but serious complication. This paper reports a 64 year old male patient who was admitted to the hospital for "left hip pain with limited movement for 2 days after falling from a farm vehicle". According to the X-ray results, the patient was diagnosed as left intertrochanteric fracture (AO type 31-a1.2, Evans Jensen type IIA). The examination was completed and the operation contraindication was excluded. The closed reduction and intramedullary nail fixation was performed on the 4th day after admission. The operation was smooth, the fracture alignment was good, and the suture was removed and discharged. Three months after the operation, the patient was hospitalized again due to swelling and pain of left thigh. The diagnosis was: delayed hematoma formed after PFNA fixation of left intertrochanteric fracture, which was cured after active treatment. Through literature review, the possible causes, clinical manifestations and treatment methods of delayed hematoma were analyzed, and it was clear that prevention was the best treatment.