Objective To explore the effectiveness of Ilizarov external fixation without bone graft in the treatment of atrophic femoral shaft nonunion. Methods The clinical data of 12 patients with atrophic femoral shaft nonunion admitted between October 2010 and January 2017 were retrospectively analyzed. There were 8 males and 4 females, aged from 24 to 61 years, with an average age of 41.7 years. The nonunion sites located in the middle and upper femur in 7 cases and in the distal femur or supracondylar in 5 cases. The disease duration ranged from 1 to 9 years, with an average of 3.7 years. Previous operations ranged from 1 to 9 times, with an average of 2.8 times. The original fixator was removed, the fracture end of nonunion was debrided, and Ilizarov external fixator was installed. In patients with the length of bone defect less than 4 cm, direct compression fixation was performed during operation; in patients with limb shortening more than 2.5 cm, proximal femoral osteotomy and bone lengthening components were required to prepare limb lengthening after operation; all patients did not receive bone graft. The wearing time of external fixator, clinical bone healing time of nonunion fracture end, and complications were recorded. The effectiveness was evaluated by Paley’s nonunion evaluation criteria. Results All patients were followed up 24-50 months, with an average of 30 months. Bony union was achieved in all 12 cases with a healing time of 6.0-23.5 months (mean, 11.5 months). The wearing time of external fixator ranged from 7 to 25 months, with an average of 13.5 months. At last follow-up, according to Paley’s nonunion evaluation criteria, the results were excellent in 6 cases, good in 4 cases, and fair in 2 cases, with an excellent and good rate of 83.3%. Sagittal angulation deformity of femur more than 7° occurred in 4 cases, with no significant effect on knee extension function, and no special treatment such as osteotomy was performed. Two patients had shorter limbs (>2.5 cm) after operation and were replaced by high shoes; 4 patients with trans-knee fixation lost knee joint mobility of 10-30° after operation; 10 cases of needle tract infection occurred, of which 4 cases with infection and loosening of fixed needle were replaced and re-fixed after needle extraction, the remaining 6 cases of infection without loosening of fixed needle were controlled by local dressing change, needle nursing, and oral cephalosporin anti-inflammatory drugs. No complications such as deep infection and vascular nerve injury occurred. Conclusion Ilizarov external fixation has a high healing rate for atrophic femoral shaft nonunion, which is relatively minimally invasive and can avoid bone grafting. Its preliminary effectiveness is exact, and it is also effective for patients who have experienced multiple failed operations. It is necessary to pay attention to the nursing and rehabilitation training after external fixation.