Objective To evaluate the effect of elastic intramedullary needle combined with Ilizarov external fixation in the treatment of large segment defect. Methods The clinical data of 51 patients with bone defect and nonunion of tibia were analyzed, of which 24 were treated with simple Ilizarov technique(group A)and 27 with elastic intramedullary needle and Ilizarov external fixation(group B). During the last follow-up, the quality Paley score, lower extremity manual line and angular formation, external fixation index(EFI), and joint function score were recorded and compared in two groups of patients. Results The 51 patients were followed up for(2.5±0.5)years. The fracture healing time was not different between A and B group(P>0.05). At the last follow-up,for groups A and B respectively, the quality Paley score of fracture healing was 66.67% versus 77.78%, EFI(1.41±1.52)vs(1.98±0.81), the AKS knee function score(118.11±17.12)vs(159.71±9.86), the functional score of the Baird Jackson ankle joint(77.02±7.27)vs(89.31±6.68), healing quality(28.58±3.22)vs(39.02±2.81)and the total effective rate of treatment 58.33% vs 88.89%. The difference between the 2 groups were all statistically significant(P<0.05). Conclusion Elastic intramedullary needle combined with Ilizarov external fixation for the treatment of large bone defects can effectively improve the efficacy and reduce complications, and is worthy of clinical promotion.