［Objective］To compare the therapeutic effect of lateral position and supine position in proximal femur intramedullary nail anti-rotation system(PFNA) internal fixation for treating the femoral subtrochanteric fractures.［Methods］A retrospective case-control study was conducted on 67 patients with femoral subtrochanteric fractures admitted to the 960th Hospital of the PLA Joint Logistic Support Force from January 2015 to June 2019, including 44 males and 23 females, with mean age of (47.13±13.12) years. According to the Seinsheimer classification, there were 15 type Ⅰ, 17 type Ⅱ, 19 type Ⅲ, 9 type Ⅳ and 7 type Ⅴ cases. Of them, 39 patients were stabilized by PFNA internal fixation in lateral position(lateral group) and 28 patients in supine position(supine group). The perioperative and follow-up data were compared between the two groups.［Results］All patients completed operation successfully without severe implications, such as neurological or vessel injuries. The operation time, intraoperative blood loss, incision length, fluoroscopy frequency and in-hospital time of lateral group were all less than those of supine group, with significant differences (P<0.05). Patients were followed up for an average of (15.91±1.74)months. The Harris hip scores of lateral group at 1 month after surgery were significantly higher than those of supine group (P<0.05). There were no statistically differences in fracture reduction quality and healing time and Harris hip scores at 6 and 12 months after surgery between the two groups(P﹥0.05).［Conclusion］Compared with the traditional supine position, the lateral position in PFNA internal fixation needs no traction bed and can shorten the operative time, reduce the blood loss and fluoroscopy frequency and help early recovery of hip function. Therefore it is a better surgical position.