Abstract: Based on the data from casing damage of Oil wells and water wells, the authors analyse the cause of casing damage in aspects of geological factors, completion quality, high pressure water ingection, downhole operation and production management, and provide the maesures to extend casing life and avoid casing damage combining with the production. Considering the factors of difficulty of workover, pressure and technology, the authors also have evaluated the economic efficiency and give the operating guidelines for workover in the casing damage wells. Additionally, have put forward the suggestions in protecting casing, saving workover fee, reducing costs and increasing economic benefits.