The interference of two circular cylinders has been researched for many years. In this study, the researchwork was concentrated on two cylinders in some special staggered arrangement. The velocity signal was measured with a hot wire anemometer and recorded with a TEAC portable datarecorder. The relationship between spectrum and time was established by making 200 spectrum analysis in se-quence. The gap flow is unstable when two cylinders are arranged in L/D=2, T/D=1. Mainly, it can be looked asflow past a single blunt body and the Strouhal number is 0.15, The second peak arises in the power spectrum whenthe gap flow appears at irregular time interval. Sometimes it may be higher than the first one. The Strouhal num-ber corresponding to the second peak is 0.33. But at most of the time it is lower than the first one and even disap-peared. This is meaningful for exploring the mechanisms of interference induced oscillations in flow past two cylin-ders. The interference of two circular cylinders has been researched for many years. In this study, the researchwork was concentrated on two cylinders in some special staggered arrangement. The relationship between the velocity of the aneurysm and the TEAC portable datarecorder. between spectrum and time was established by making 200 spectrum analysis in se-quence. The gap flow is unstable when two cylinders are arranged in L / D = 2, T / D = 1. Mainly, it can be looked asflow past a single blunt body and the Strouhal number is 0.15, The second peak arises in the power spectrum whenthe gap flow appears at the irregular time interval. Sometimes it may be higher than the first one. The Strouhal num-ber corresponding to the second peak is 0.33. But at most of the time it is lower than the first one and even disap-peared. This is meaningful for exploring the mechanisms of interference induced oscillations in flow past two cylin-ders.