Abstract: The property target values of the TP140V oil casing for extra-deep complex well service are designed on the basis of in-deep investigation and analysis of the service conditions and loading characteristics of the casing in the extra-deep complex well,and analysis of the typical failure cases of the casing.Taking the actual circumstances of relevant equipment,the specialty steel type is also designed,and associated manufacture process and the key technological measures are determined.All the property target values of the casing produced as per the designs are in full conformity to the specified design requirements.After successfully trial-used in the extra-deep complex well in the oil field,the said casing has been spread,and used in the major oil fields of the country.