Objective: To investigate the effect of bone peptide injection combined with PFNA internal fixation on serum bone metabolism in elderly patients with intertrochanteric fracture of femur. Methods: 83 elderly patients with intertrochanteric fracture of femur admitted to our hospital from January 2018 to June 2019 were selected as fracture group. They were randomly divided into two subgroups. The control group (n=60) was treated with PFNA, anti-infection and anticoagulation after operation, and functional exercises were taken. The study group (n=60) was given intravenous bone peptide injection for one month on the basis of the control group. 60 non-fracture elderly healthy persons were selected as healthy group. Blood samples were collected before and after treatment in fracture group and healthy group to measure bone metabolism. Bone mineral density (BMD) was measured by X-ray absorptiometry before and after treatment in fracture group.The recovery of hip joint was followed up for 6 months. Results: The serum levels of PINP and CTX in fracture group were higher than those in healthy group (P < 0.05), while the levels of BGP and 25 (OH) D3 were lower than those in healthy group (P < 0.05). One month after treatment, the levels of PINP and CTX in study group and control group were both higher than those in healthy group (P < 0.05). After treatment, BGP, 25 (OH) D3 and BMD increased in both groups, and there was significant difference between the study group and the pre-treatment group (P < 0.05), while there was no significant difference between the control group and the pre-treatment group (P > 0.05). After that, serum 25 (OH) D3 in the study group was higher than that in the control group (P < 0.05). Pearson correlation analysis showed that serum PINP and CTX were negatively correlated with BMD in fracture patients (P < 0.05).Six months after treatment, the excellent and good rate of hip joint function recovery in the observation group (95.00%) was higher than that in the control group (81.67%), the difference was statistically significant (P < 0.05). Conclusion: Osteopeptide injection combined with PFNA internal fixation can effectively improve serum PINP and CTX levels in elderly patients with intertrochanteric fracture of femur, increase bone mineral density, promote bone healing and hip function recovery.