EPC thermal power plant project（ 4 × 330 MW） adopted the boiler（ oil / gas） at middle east. During the commissioning phase,vibration occurred at tail duct and economizer of boiler. After analyses and calculation,vibration was found to be resulted from closeness of the Karman vortex to the acoustic wave frequency of the boiler mainly. Anti-vibration baffle plate had been installed and the vibration had limited. We hope it useful for the Boiler（ oil / gas） of EPC project.