Abstract: Briefly introduced in the paper are the background for R & D of C110 casing and technical progress of metallurgical manufacturing process abroad.Actual operations of some manufacturers are compared with the requirements of API Spec 5CT for alloying design and process control of this grade.Also introduced are the applicability evaluation and actual application cases of C110 casing, and proposed are the relevant suggestions for the development and production of C110 steel and C110 casing.