Abstract Objective To explore the clinical effect of modified anterolateral approach in the treatment of type C fractures of distal femur. Methods 86 patients with type C fractures of distal femoral were randomly divided into two groups, 43 cases were in each group, all patients in two groups were treated by open reduction and internal fixation operation, the treatment group received modified anterolateral approach, the control group received traditional anterior lateral approach, compared the operation time, intraoperative blood loss, fluoroscopy times, postoperative function exercise time and the time of fracture healing of patients in two groups, and compared Hiss scores of knee joint in 3, 6, 12 months after surgery and the excellent and good rate of knee joint function in 12 months after surgery. Observed and compared the incidence of complications of the two groups. Results The two groups were successfully completed the operation, the operation time and fluoroscopy times of the treatment group were less than that of the control group (P < 0.05), there was no significant difference in the amount of bleeding during the operation(P > 0.05), the exercise time after operation and fracture healing time of the treatment group was less than that of the control group after operation(P < 0.05); Hiss of patients in the two groups in 3, 6, 12 months was gradually increased, the treatment group was higher than those in the control group (P < 0.05); The excellent and good rate of function of knee joint in 12 months after surgery was higher than that of the control group (P=0.035); The incidence rate of complication was low and there was no significant difference (P=0.243). Conclusion The modified anterolateral approach in the treatment of type C fractures of distal femur can be fully exposed, reduce muscle injury, shorten operation time, reduce the times of perspective to fracture, and it is in favour of anatomical reduction and recovery of knee joint function.