In order to study the connection performance and sealing performance of HST special threaded casing joints under tight working conditions and tensile conditions, ABAQUS finite element software is used to analyze the stress and contact pressure of the joint torque shoulder, sealing surface and thread teeth under the two working conditions by changing the interference amount of the sealing surface of the pipe body and the coupling and the force of the pipe body. Through analysis, it is obtained that the maximum interference of the sealing surface of the pipe body under the tight working condition is 0.09mm, and the joint connection performance and sealing performance are weakened under the tensile condition. The research in this paper provides theoretical guidance for the practical application of HST special threaded oil casing.