Objective To investigate the role of the distal fourth fixation factor in the treatment of unstable femoral intertrochanteric fractures with intramedullary nails. Methods A total of 108 patients with unstable femoral intertrochanteric fractures (AO type:A2.2-A.3.3) treated from Jun. 2014 to Jun. 2018 in our hospital were selected and divided into three groups. The injury was fixed with short intramedullary nails and had matched medullary cavity in group A (n=42). The injury was fixed with short intramedullary nails and had mismatched medullary cavity in group B (n=40). The injury was fixed with long intramedullary nails in group C (n=26). Operation time, intraoperative blood loss, fracture healing time, postoperative complications and clinical efficacy were compared among the three groups. The efficacy was evaluated by the Harris hip score. Results There was no significant difference in the age, gender composition, or causes of injury between groups (P>0.05), but there was statistic difference in the AO type between groups (P<0.01). The operation time of group A was (62.26±31.03) min, which was significantly shorter than that of group C ([89.54±26.70] min, P<0.05), but not statistically different from group B ([64.53±29.22] min, P>0.05). The amount of intraoperative bleeding in group A was (149.19±45.97) mL, which was significantly less than that in group C ([230.77±57.40] mL, P<0.05), but not statistically different from group B ([153.43±40.30] mL, P>0.05). The fracture healing time in group B was (14.10±2.22) months, which was significantly longer than that in group A ([11.43±2.95] months) and group C ([12.35±4.47] months, P<0.05). At the last follow-up, the Harris score in group B was 77.33±8.18, which was significantly lower than that in group A and C (85.52±10.76, 89.12±9.14, P<0.05). Two patients in group A developed coxa vara. Eight patients had lost restoration in group B. No complications occurred in group C. There was significant difference in the incidence of complication among the three groups (Fisher exact test, P=0.013). Conclusion The technique using the distal fourth fixation factor can reduce the complications of unstable femoral intertrochanteric fractures such as postoperative loss of restoration and internal fixation failure, shorten the fracture healing time, and achieve early weight-bearing exercise.