[Objective] To investigate the risk factors associated with postoperative internal fixation failure in the treatment of femoral intertrochanteric fractures with proximal femoral nail fixation (PFNA). [Methods]: The clinical data of 240 cases of intertrochanteric fractures treated with PFNA internal fixation from January 2013 to June 2017 were retrospectively analyzed. A Logistic regression model was established to analyze risk factors that could lead to internal fixation failure. [Results]: 240 patients were lost to follow-up in 56 cases, and the remaining 184 patients were followed up for 24 months. Of the 184 patients, 32 had internal fixation failure, 11 had hip varus, 7 had retraction, 9 had internal fixation, and 5 had nonunion. The remaining 152 successful patients had a Harris function score of 24 months after operation: excellent in 20 cases, good in 78 cases, moderate in 50 cases, and poor in 4 cases. The excellent and good rate was 64.47%. In the 32 patients with failure, the Harris function scores were 3 months after the internal fixation failure: excellent in 0, good in 4, fair in 5, and poor in 23. The excellent and good rate was 12.5%. Univariate analysis showed that the thickness of the lateral wall, the tip margin (TAD), the orthotopic difference, the lateral wall classification, the Singh index, and the fracture classification were associated with internal fixation failure (P<0.05), while gender, age, and lateral position. The position difference and spiral blade area were not related to the internal fixation failure (P>0.05). Logistic regression analysis suggested that TAD, lateral wall thickness, Singh index and fracture classification were risk factors for internal fixation failure (P<0.05). [Conclusion]: TAD, osteoporosis degree, lateral wall thickness and fracture stability are risk factors for internal fixation failure, and the failure of internal fixation will seriously affect the hip function of patients.