Objective To explore the failure causes of mastoidectomy and precautions.In order to improve surgical skills.Methods The operation findings of 45cases who underwent revision mastoidectomy from 2000 to 2007 were analyzed for causes of the primary procedures and revision mastoidectomy failure.Results Original symptoms disappeared.All cases achieved a dry ear after mastoidectomy 1~3 months.Conclusion Causes of failure of mastoidectomy include many.To eliminate pathological tissue thoroughly,to remain good drainage after operation,to manage some execptions are keys to prevent reoperation.