Infected bone nonunion, chronic osteomyelitis and large bone tumors can cause bone defects, especially involved parts more than 20% of the length, are difficult to treat in clinical practice. For the above cases, Ilizaroy technique is used and has attained good curative effect in the department. By using the technique, there are a lot of advantages, such as shortened curative time, better bone healing, low-damage to joint, minimal wound and less complications. To sum up, the whole curative effect is much better than the traditional one, especially under the infectious cases. If complications happened, the technique also has better management to it.