Abstract: Described here in the essay are the major amendments of the new edition API Spec 5CT, API Spec 5B and API RP 5C5, and also analyzed here are the influences by the changes of these API specifications on property requirements for the tubing/casing.The discussion focuses on the specifications and methods for evaluation of premium connection air-sealing, evaluation of gas storage well-service casing, evaluation of shale gas well casing, and perforation interval casing.The analysis identifies the facts as follows.Compared with the previous editions of the specifications, the new edition API Spec 5B, is added with measurement of thread diameter and ovality, and related requirements;the 9th edition API Spec 5CT is added with the C110 casing, while API RP 5C5-2017 is added with evaluation of performance of the connection under high temperature service conditions.It is revealed via the major changes of the specifications for the tubing and casing that in order to meet the need for exploration and exploitation of unconventional wells, the requirements for properties of tubing and casing are mainly related to sealing performance, high temperature-resistance, corrosion resistance, high collapse resistance and connection ant-fatigue property, etc.of the premium connection.