Abstract: In connection with the casing failure wells in Shengli oilfield,investigations have been made throughout and relevant data has been collected.According to the five basic types of reservoir in Shengli oilfield,analyses has been conducted about the law and reasons of casing failure with the statistics method considering sand influx,performation,water injection,corrsion,acid treatment and fracturing,steam injection,casing srength design,cementing quality etc.It is considered that the casing failure is a result effected by multfactors and the study directions are put formard in the future according with the present situation of casing failure.