In view of the potential safety hazards easily caused by the vibration of isolated phase enclosed bus, the vibration mechanism and response simulation analysis will be carried out in the paper. Taking the fully connected isolated phase enclosed bus with horizontal arrangement as an example, the dynamic model is established. The mechanisms of bus vibration response under short-circuit fault and earthquake are analyzed, and simulation and comparative analysis are carried out. The results of the analyses verify that the bus vibration does exist, and the harm caused by vibration intensity can not be ignored. This study provides a theoretical basis of bus vibration analysis and vibration reduction.