Abstract: To mitigate the threat of slope failures to highway networks in the Western Yunnan red bed region of China, shaking table experiments were conducted on a representative slope prototype. The dynamic response and failure mechanisms of the slope were analyzed under seismic action and coupled seismic-rainfall conditions using peak ground acceleration (PGA) amplification factors, pore water pressure, Hilbert-Huang transform (HHT) marginal spectral peaks (PMSA), and failure mode observations. The results indicate that under both conditions, PGA exhibited"elevation amplification" and"surface amplification" effects, with surface amplification gradually decreasing as elevation increased. Under seismic action alone, PGA showed a regular correlation with acceleration intensity, whereas under coupled seismic-rainfall conditions, this relationship became irregular. Rainfall significantly increased instability risks and damage severity in the upper slope compared to seismic action alone. Pore water pressure was positively correlated with elevation and seismic amplitude, with the strongest seismic response amplification observed at the slope crest. PMSA curves confirmed that failure progressed from the crest to the midslope in both scenarios. Under pure seismic action, slope failure occurred at 0.7g acceleration through sequential stages: crack development → stratum bending → intense bending → collapse, characterized by crest bending-tensile failure. Under coupled seismic-rainfall conditions, instability initiated earlier at 0.4g acceleration, progressing as follows: rainfall-induced crest disintegration and surface sliding → crack propagation and stratum bending → intense bending → failure, resulting in composite disintegration with combined bending-tensile and creep-tensile damage. This study provides critical references for slope design and hazard mitigation in Western Yunnan red bed areas, contributing to enhanced highway safety.