Abstract: In order to analyze the progressive collapse dynamic response and collapse resistance of an isolated structure subjected to multi-directional coupled dynamic excitations, the motion equation of an isolated structure under this occasion is established. The nonlinear dynamic responses of the isolated structure considering only vertical imbalance and multi-directional dynamic coupling excitations are analyzed, and a random robustness index based on reliability theory were derived to evaluate the progressive collapse ability of the isolated structure. The results show that the dynamic response of the isolated structure is greater under a multi-directional dynamic coupling excitation. After bearing fails, the time required for the internal force redistribution of the structure to reach a new equilibrium is longer, and the collapse resistance of the structure is lower.