<p>Slender-strip entangled metallic pseudo-rubber (SS-EMPR) has considerable potential for pipeline support and vibration isolation in confined spaces. However, its dynamic degradation behavior and fatigue life prediction under variable amplitude-frequency loading remain insufficiently understood. In this study, a multiscale analytical framework was established by integrating macroscopic hysteresis decomposition, parameter identification, microscopic damage characterization, and fatigue life modeling based on steady-state sinusoidal dynamic tests and long-term fatigue tests. The results show that increasing the excitation frequency from 1 to 10 Hz reduced the dynamic stiffness by 16.2% and increased the energy dissipation per cycle by 14.5%. When the vibration amplitude increased from 0.3 to 1.0 mm, the energy dissipation per cycle increased nearly fivefold, while the dynamic stiffness increased by 45.1%, indicating enhanced inter-wire frictional sliding and elastic energy storage. Under cyclic loading, the macroscopic hysteresis loops continuously contracted, accompanied by the progressive degradation of linear stiffness, cubic stiffness, and equivalent damping. At the microscopic level, this degradation corresponded to the contact network evolving from rough interlocking to polished surfaces and third-body-layer-dominated states, and finally to microcrack initiation and propagation. Based on the normalized degradation of these characteristic parameters, a combined damage vector and a maximum-norm-based failure criterion were proposed. By incorporating a power-law frequency-correction factor into a two-parameter Weibull model, a unified fatigue life prediction method was established for the representative low-frequency operating range studied. The predicted nominal life decreased by 12.6% as the loading frequency increased from 3 to 5 Hz. The proposed framework provides a quantitative basis for fatigue life evaluation and maintenance planning of piping systems operating in confined spaces.</p>