Abstract: Described in the assay are the basic structure and main design idea of a new high torque and gas tight casing with the WSP-NF premium connection for rotating-casing cementing service. The methods and principles as used for the design of the casing connection’s anti-torque function and gas sealing function are discussed with the FEA method,and then verified by relevant full-scale tests.Resultsof related calculation and the tests demonstrate that the WSP-NF connection is in possession of an advanced torque shoulder and reasonable metal-to-metal seal structure,hence it is free of the weak points of the API connections and the convenient premium connections as well,which makes it having excellent torsion resistance,and the gas seal pressure as equal to inner surface yield stress of the pipe. The result of the above mentioned study is worth referencing for further development of casings with premium connections as suitable for actual service conditions of oil/gas fields.