Abstract: Steel ejector tube is widely used in aviation andchemical industries as an exhaust apparatus in product experiments. However, theinternal high-speed airflow can result in a large number of longitudinalcracks around the cylinder. It is related with vibration modes and frequencies, as well as the stress level of the ejectortube. In this work, the petal breathing vibration mode and frequencycorresponding to the longitudinal cracks in a large ejector tubestructure are studied using FE analysis. With dynamic stress analysis, the frequencywhich leads to damage of ejector tube is found mainly in the lowfrequency band of 200\sim 300\,Hz. A typical breathing vibrationmode and frequency were obtained through experiments, which shows that thenumerical modeling and analysis are reasonable.