To prevent casing-cement sheath bonding interface failure in Gas storage wellbore, it is essential to understand the integrity failure mechanism of the bonding interface under alternating temperature. In this study, a self-developed experimental apparatus was used to simulate the wellbore load environment. Tests and evaluations were conducted on the sealing and mechanical properties of two full-scale" production casing- interface-ductile cement (conventional cement)-intermediate casing" assemblies under alternating loads on the production casing. The sealing failure number and bonding strength were utilized as characterization parameters for sealing and mechanical properties. The integrity test results for conventional and ductile cement under alternating peak tempertature of 40 ℃, 70 ℃, and 100 ℃ were obtained. The experimental results demonstrate that the sealing failure number of interface exhibits an exponential relationship with the alternating peak temperature. Specifically, the bonding strength of interface between casing and conventional cement decreases linearly with the increase in alternating cycles, whereas the bonding strength of interface between casing and ductile cement decreases exponentially with the increase in alternating cycles. Furthermore, the study analyzes the influence of alternating peak temperature and cycle number on integrity and interfacial mechanical properties. It clarifies the correlation between sealing performance and mechanical properties and elucidates the sealing failure mechanism of interface between casing and cement sheath under alternating loads.